It is best to practice for short periods at first, especially while your fingers and arm muscles are still developing. If you want to become a great player you will obviously have to practice more as time goes on, but it is still better to work on new things a bit at a time. Get one small piece of information and learn it well before going on to the next topic. Make sure each new thing you learn is thoroughly worked into your playing. This way you won’t forget it, and you can build on everything you learn.
Once you feel you are ready, try to play with other musicians as often as possible, especially bass players and drummers. If you can become a good rhythm player or accompanist, you will always be popular with other musicians and vocalists. It is in a group situation that you will find out how much you really do or don’t know, and it is also a lot more fun than practicing by yourself all the time. Good luck and have fun with your music.