This is a general timeframe when you will deal with these challenges. It's not meant to be an exact accounting of dates, but it should cover the time that you anticipate facing these issues. For example, if you're going to be shopping for gifts and food at regular intervals from mid-November till the end of December, that will be a part of your life for the duration - even if you're not shopping at a certain moment, it will still be on your mind, and you'll still be dealing with it. So, even if you only actually shop for four days of the four weeks, until it's all done, it's a challenge you're facing.
Estimate the range of days that each item will take over a three month period between November and January. For example, if you spend two days shopping for gifts and have two holiday meals, an office party and neighborhood potluck that you will need to purchase food for this might be a total of 6 specific days spread out between November 24 and January 3.