If you're new to exercising, you should meet with your coach two or three times a week. After that, you can meet with your coach when you feel you need inspiration or specialized training. For a patient to achieve optimal benefits soon after diagnosis, most doctors initially prescribe three visits per week. Your physical therapist will advise you on the appropriate number of visits after the initial evaluation.
The budget is going to be an important factor, because, of course, more sessions are going to be more expensive. Don't worry, even if you can only afford one session per week, it will still be a big benefit. You'll have to be accountable to your coach and you can still learn a lot even with just one session per week, so don't give up personal training just because you can't do all the training with your coach.