Show Specific Content Based on Month

<?php
/*
Plugin Name: Content Based on Month
Description: Displays 1 of 2 sets of content every 2 months and switches automatically. Also provides an expiration shortcode.
Author: Onlineth
Version: Beta
*/
/*
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
 */
function content_set1( $atts, $contenttext1 = null ) {
    $date = date('F');
    switch ($date) {
        case 'January':
        case 'Febuary':
        case 'May':
        case 'June':
        case 'September':
        case 'October':
            return $contenttext1;
    }
}
function content_set2( $atts, $contenttext2 = null ) {
    $date = date('F');
    switch ($date) {
        case 'March':
        case 'April':
        case 'July':
        case 'August':
        case 'November':
        case 'December':
            return $contenttext2;
    }
}
function lastdaymonth(){
    $month = date('m');
    if ($month % 2 == 0) {
        return (new DateTime())->format("m/d/Y");
    } else {
        return (new DateTime("+1 month"))->format("m/d/Y");
    }
}
add_shortcode('expiration', 'lastdaymonth');
add_shortcode('content1', 'content_set1');
add_shortcode('content2', 'content_set2');
?>