If you've learned something new or revised something old then no matter how long it took, be it 10 mins or 4 hours, then that is good enough per day. I find trying to make schedule bothersome, it actually discourages me. Obviously for some people they find it good to have a set routine of some sort for learning, but I'd rather learn whenever I had the time throughout the day using various learning tools.
Also something important to note is that it depends on your frame of mind when you want to study, because in the end it's not something you have to do, so if your having a crappy day then you might think "I'll make up for it tomorrow" or whatever and that kind of thinking leads you downhill fast most of the time.
Last thing, don't try too much, you've been studying 3 weeks? Then its touch and go, if you do too much you'll burn out, keep it at a pace you feel you can not should. And most importantly, enjoy it.