Practicing is one of the most important skills in learning any instrument. There is no magic number of days per week or hours per day to practice to learn. Practicing consistently is the most important thing, setting a schedule and sticking to it is important. You should decide on the number of days per week that you want to practice and then do it. IF you can practice every day do it, if you can only practice MWTF then do that. Most importantly stick to this practice schedule week after week.
The next step is smart practicing, while it's fun to play the stuff you know, that doesn't help you learn. When you sit down start with the most troubling spot. Think about it, play it through slow, maybe even once on each hand. Once you get it right don't stop, play it 3-5 times more correctly to commit it to your brain. Then play the section that includes that part, and play it a few times. When you think you have run out of things to practice play the whole piece through and think about where you slowed down or felt shaky.
DOs and DONTs
DO write things in your score especially write a note name if you missed it a few times
DONT practice really fast something that is wrong
DO play something over and over again