Social security and working

Hi, I applied for social security and plan on working the alotted 45 hours per month.  At first I was unable to get my employer to state I would only work 45 hours a month (I work per diem and control my own schedule).  So I had to quit my job.  Now, I am able to receive a letter that states that I would not work more than 45 hours a month.  I am at the end of the process (I believe) for approval.  I am not sure if I should wait to work once I am approved and then send in the paperwork.  Or just send it in now, which could postpone my benefits. 

Anyone have experience with this.