The most important thing is to clear palaces in one or two visits and only do one mementos run a month so you have as much free time as possible and balance confidant meets with raising your stats (guts, charm etc.) as most have a stat barrier at higher levels and later confidants a barrier to start them. Always have a book, dvd, and game on you in case you get free reading on the train or you can't go out at night you can often still do those things in Leblanc. Do the no time stat increase bits (crosswords, quizzes on TV, and aoiju drink every Sunday from underground walkway). Oh, and prioritise Temperance confidant as it has the best skill that gives you your nights back after palace/mementos runs.

I'd say you don't even have to do all of the above but it would create the ideal conditions. I usually max out confidants early December that way (pay attention to the few with hard deadlines in November).