Your questions are asked and answered on several threads on this website, look around. Your concern about maintaining a good pace of training is astute, generally 3 times a week is considered an optimum pace but if you schedule only 3 flights a week you will likely fly less, possibly a lot less. The unknown is how weather will affect your schedule, which is greatly affected by the time of year and where you are geographically in the country (The more northern, the more weather is going to impact how many flights get cancelled). The other factors are the quality of the school, whether your instructor is very busy and soon to leave for greener pastures, how well the school fleet is maintained, and lastly, how much money you can put towards your training and at what rate.
Working while training creates conflicts where usually your training winds up on the loosing end. Best bet is to set aside all the money to get you to your goal (Zero to hero, figure about 70K, give or take). If you can do so, don't work while running the table on your training, but that's a consideration only your can answer.