There isn't a time limit or ruining there week by letting them know you need help. You wont know the outcome of asking for help until your receiving help, there is no crystal ball to tell you how you will or will not be helped.

Just sit down with your parents and explain to them that your having trouble and need help. If you don't think you can verbally say what you need to , then write it down and let them read it.

Take care and welcome to PC