It is best to plan a schedule for your practice, otherwise it may well get pushed aside
as you have homework to do, emails to answer, tomorrow's meeting to prepare for!
For the first year I suggest practising four times a week for 15 minutes in a quiet place where you can concentrate well. Write down the days and the time when you are going to practise.
Warm up by practising some scales. Practise slowly and accurately to start with. Once you know a scale by heart, we will work to increase the tempo.
Look at what you have been asked to practise for the week. Some days concentrate on particular parts of the pieces where you need to improve. Other days, play all the pieces to the point you have currently learnt them.
Do not rush to begin with, know your pieces and scales well and then a faster, accurate tempo will follow.
After the first year as you progress onto more difficult pieces, the length of time for practice will need to increase. However, the tips above will still apply. Each day, think about what it is you are going to practise, what is it you are trying to improve upon?