var originalProceedWeek = General.proceedOneWeek; //store the original function as a variable
var myProceedWeek = function(company, customweek) //create a new function that will override the old one
{
    originalProceedWeek(company, customweek); //call the original we stored

    if (company.currentWeek < 1) { //check if the date is before 1/1/2
        //do something at 1/1/1
    }
    else if (company.currentWeek > 0 && Math.floor(company.currentWeek) % 4 === 0) { //check if the date is later than 1/1/1 and the current week is divisible by 4, the number of weeks a month
        //do something every month
    }
};
General.proceedOneWeek = myProceedWeek; //replace the original function