Well, I can't give an exact answer, as much depends on luck. However, what I will say is that it is much faster than it was in previous generations to get flawless IV's. This is because of two new things: The Friend Safari and the Destiny Knot.
The Pokemon in the Friend Safari are guaranteed to have at least 2 perfect IV's. In fact many of the one's I have caught actually have more than two, so I'm guessing the chance of getting that is also increased, but at least two is guaranteed.
The Destiny Knot will pass 5 IV's down to the offspring from either parent. So if you already have two Pokemon with high IV's, then the offspring will get most of those perfect IV's. Of course, which ones are passed is down to luck, but hatch enough eggs and you should get there.
So because of these things it is a lot easier than in previous generations. But yes, it is still time consuming. Personally, I am too lazy to get 6 perfect IV's in any Pokemon. But I usually try for at least a couple of useful ones.
So to make a full team of six will take planning, and it will take time. It will also take longer if you don't have the Pokemon you want in a Friend Safari, but keep at it and you will get there eventually. The worst part is getting your team of 6, and then keep getting decimated online because of something you didn't consider, like a common in weakness in most of your Pokemon to a certain type or whatever. For that reason it is usually best to trial the team you want on Pokemon Showdown or another battle simulator before putting in the effort of getting that team in-game. That will allow you to refine your team more easily, before you create them in your game. That at least makes sure that your time doesn't go to waste.
If you are worried about having enough time, then perhaps just start as you can, but wait until the Christmas holidays before putting real dedication into it. It isn't like the game is going anywhere between now and then.
I hope this helped.