There's a difference between just being able to play, and being able to play with other people. It's never to early to start learning that, and the more you play with a group the better off you'll be in the future.
But, if there are four of you forming a band and all of you are new to music, you can end up in a "blind leading the blind" situation. Many if not most beginning bands waste a lot of time and energy focusing on the wrong things and don't get their act together, despite this being the time in your life when you'll probably have the most opportunity to spend a lot of time on music.
I highly recommend finding somebody with some band experience to come by, listen to what you're doing, and give you tips. If one of you has a bass/guitar/drum/keys teacher you like and respect, that would be a good place to start. Or if you know somebody who's in a working band.
Often it's easier to accept a comment like "the guitar is too loud" or "that riff is wrong" from a disinterested outside observer than a bandmate.
Also, it is likely that as you develop, you will either (a) develop at different rates, or (b) develop in different directions. It's great to be in a band with people who are also your pals, but don't get too heavily emotionally invested in this particular project, because within a year or two you may well be facing the prospect of either quitting, or kicking one of your friends out, or at least having one or more of them quit. If you're serious and have talent, you will almost certainly be in LOTS of bands over the course of your life. Make the best of this situation, but if it becomes apparent that the other people want different things out of it (or aren't willing to do what's necessary to achieve what they say they want), be prepared to move on. Maybe your group is the exception and you'll be together for the long haul, and if so great, but it doesn't usually work out that way with first bands.
That point is related to another common issue in new bands: if any of you are going to sing, you will need a PA of some sort. DON'T jointly buy a PA. It may seem like a good way to get the money for one, but it almost inevitably leads to bad situations and bad feelings down the road. There are threads about that here, but it's best for one person who can scrape the resources together to get a PA, or if that is impossible, have each member buy discreet components, i.e., one person buys some mics, one person buys a mixer, other people buy wedges, etc. The singer or keyboard player would be the ones with the biggest interest in the PA at this point, so they would be the obvious ones to get it if they can, but it will never hurt anybody to own a PA. Also, I think it is quite reasonable to require everybody to provide their own powered speaker to use as their own monitor, although it may be easier to find a powered mixer and unpowered cabinets.