Congrats. Just took delivery of mine today after 7 months of having a Model 3.
Lots of debate on this. In my opinion there are two schools of thought, one super in-the-weeds, the other not so much:
1. Figure out a charge limit that allows the car to sit as close to 50% as possible for as long as possible (in theory this is best for the battery long term). For instance, I set my charge limit to exactly 57% and I schedule charging using the off-peak hours to end right when I leave for work. I drive to work and end up there at about 54%, the car sits at that SOC while I'm at work, then I depart and arrive home right at 50% give or take where it sits until the whole thing repeats. On the weekend I usually set it to 55%. I'm weird so I actually enjoy this sort of granular charging habit and wish I had more control over it in the app.
2. Set the charge limit to 80 or 90 and don't worry about any of that above.
I'd go with whichever method sounds the best for you. If you never want to worry about it, set it to 90 percent and never think about it again (or 80% doesn't really matter, might be slightly better for the battery long term). If you like the sort of thing described in #1 then go for that.
Edit to add that setting it to a lower SOC will mess with the car's ability to estimate the range (though not its actual range), which is why Tesla recommends 90%. Lots of threads on this if you do a search, especially in the Model 3 forums.