The first 5 months from date of original file date = no back pay unless you have a earlier date of disability then you can wind up with back pay.

Attorneys can only charge you 25% of your back pay. If you have no back pay there is a cap limit you can be charged by attorney.

Have you filed yet ? Or just gathering info ?

Most Attorneys offer a free appt to see how likely you are to be awarded. Normally they won't take a case they can't win.