Is it worth it working as a Casual Clerk for USPS?

I've already passed the 473 exam, had an interview, got the position, did paperwork, fingerprints, took driving exam 804-passed. Now I'm going to training from Mon-Thursday for sure and possibly Friday. It's 119 miles from me so I have to get a hotel room. We have to pay for everything upfront and get reimbursed later from the USPS. I will be paid $12 an hour and yes I know there are no guaranteed hours and can work 6 days a week or work 2 days a week. Pretty much like a slave job lol. But is it worth it? Could I possibly go to full-time? I have no job at all right now and neither does my husband so he will stay with our two children until he gets a job. So I will take the job whether it's worth it or not, just wanted opinions.