Chronological order:

                 (YEAR 0)
Hidamari Sketch x Hoshi 9.1 (first half)----22/Nov ---> Sae and Hiro in the first grade of highschool - PS.: I think you can watch this right BEFORE the second half - I would prefer to watch as first episode (the first half).
                 (YEAR 1)
Hidamari Sketch x365 01---------------------10/Feb ---> Yuno's entrance exame to the first grade of high school.
Hidamari Sketch x365 07---------------------07/Apr ---> Entrance Ceromy (begins the first year at school for Yuno).
Hidamari Sketch 11--------------------------28/Apr
Hidamari Sketch 04--------------------------18/May
Hidamari Sketch x365 03---------------------27/May
Hidamari Sketch x365 SP 02------------------06/Jun
Hidamari Sketch x365 10---------------------08/Jun
Hidamari Sketch 03--------------------------17/Jun
Hidamari Sketch x365 12---------------------08/Jul
Hidamari Sketch 06--------------------------14/Jul
Hidamari Sketch x365 06.1 (first half)------30/Jul
Hidamari Sketch x365 09.1 (first half)------05/Aug
Hidamari Sketch SP 01-----------------------11/Aug
Hidamari Sketch 02--------------------------21/Aug
Hidamari Sketch SP 03-----------------------26/Aug ---> This ep. is a short promo. about the next season (x365).
Hidamari Sketch 09--------------------------04/Sep
Hidamari Sketch x Hoshi 8.2 (second half)---26/Sep ---> You'll see, in the end of the ep., "class 2-A", but I think they missed it, and actully is 1-A
Hidamari Sketch x365 11---------------------28/Sep
Hidamari Sketch 07--------------------------12/Oct
Hidamari Sketch x365 08---------------------13/Oct
Hidamari Sketch x365 04.2 (second half)-----31/Oct
Hidamari Sketch 10--------------------------03/Nov
Hidamari Sketch x365 06.2 (second half)-----11/Nov
Hidamari Sketch SP 02-----------------------27/Nov
Hidamari Sketch x365 09.2 (second half)-----03/Dec
Hidamari Sketch x Hoshi 03.2 (second half)--10/Dec ---> It wasn't suppose to exist the numbers 103 and 203 in the mailbox of the apartments, I think they missed it, since they (the numbers) only come to exist when Nazuna and Hori move to Hidamarisou. Besides, Arisawa appears leaving the school (in 'year 2' she already graduated) and Yuno do not reconized her, which strengthen that the second half of this episode is from 'Year 1'.
Hidamari Sketch 12--------------------------25/Dec
                 (YEAR 2)
Hidamari Sketch x365 13---------------------10/Jan
Hidamari Sketch 01--------------------------11/Jan
Hidamari Sketch x365 02---------------------06/Feb
Hidamari Sketch x365 SP 01------------------10/Feb
Hidamari Sketch 05--------------------------13/Feb
Hidamari Sketch x Hoshi 11.2 (second half)--16/Feb ---> in the final two minutes there is a event happening in 07/Mar
Hidamari Sketch x365 OVA/EX-----------------24/Feb
Hidamari Sketch x Hoshi 01.1 (first half)---27/Feb
Hidamari Sketch 08--------------------------13/Mar
Hidamari Sketch x365 04.1 (first half)------16/Mar
Hidamari Sketch x365 05---------------------25/Mar
Hidamari Sketch x Hoshi 01.2 (second half)--01/Apr
Hidamari Sketch x Hoshi 02------------------06/Apr ---> Entrance Ceremony for juniors? (begins the first year at school for the juniors - Nazuna/Nori). Second half: "flashback" of a event occurred at year 1 (19/Jul).
Hidamari Sketch x Hoshi 03.1 (first half)---08/Apr ---> Entrance Ceremony for seniors? (begins the second year at school for Yuna/Miyako and third year for Sae/Miho).
Hidamari Sketch x Hoshi 4-------------------15/Apr
Hidamari Sketch x Hoshi 5-------------------20/Apr ---> In the second half, there is "flashback" of a event (in 'year 2' - 31/Jan) that they talked about in the firs half.
Hidamari Sketch x Hoshi 6-------------------26/Apr ---> There is a "flashback" (in 'year 1' - 15/Act) in this episode
Hidamari Sketch x Hoshi 7-------------------03/May
Hidamari Sketch x SP 02.1 (first half)------09/May
Hidamari Sketch x Hoshi 8.1 (first half)----13/May ---> Despite of the date, I really recommend watch this one before 'Honey 01'. You'll understand why, I think.
Hidamari Sketch x Honey 01------------------06/May ---> Despite of the date, I really recommend watch this one after 'Hoshi 8.1'. You'll understand why, I think.
Hidamari Sketch x Honey 02------------------18/May
Hidamari Sketch x Hoshi 9.2 (second half)---21/May
Hidamari Sketch x SP 02.2 (second half)-----25/May
Hidamari Sketch x Hoshi 10------------------28/May
Hidamari Sketch x Hoshi 11.1 (first half)---05/Jun
Hidamari Sketch x SP 01.1 (first half)------15/Jul
Hidamari Sketch x Hoshi 12------------------12/Jul
Hidamari Sketch x Hoshi SP 01---------------11/Jun ---> "flashback" in second half about Natsume (07/Apr)
Hidamari Sketch x SP 01.2 (second half)-----28/Aug
Hidamari Sketch x Honey 03------------------31/Aug
Hidamari Sketch x Honey 04------------------15/Sep
Hidamari Sketch x Honey 05.1 (first half)---17/Sep
Hidamari Sketch x Honey 06.1 (first half)---25/Sep
Hidamari Sketch x Honey 05.2 (second half)--28/sep
Hidamari Sketch x Honey 06.2 (second half)--29/Sep
Hidamari Sketch x Honey 07------------------05/Oct
Hidamari Sketch x Honey 08------------------11/Oct
Hidamari Sketch x Honey 09------------------10/Nov
Hidamari Sketch x Honey 10------------------02/Dec
Hidamari Sketch x Honey 11------------------22/Dec (the fist half) and 21-24/Dec (the second half)
Hidamari Sketch x Honey 12------------------31/Dec
Hidamari Sketch x Sae and Hiro--------------01/Feb
Hidamari Sketch x Sae and Hiro--------------28/Feb