Sign off job seekers allowance

I made a rapid reclaim for my job seekers and went in for for preliminary interview last Friday. My first sign on date for this claim is on the 4th April.

I got an apprenticeship offer on Saturday and started working on Monday. Normally I would sign off as soon as possible but I won't be getting paid for the first time until the 28th April.

So therefore I have a question: when do I sign off? As I won't be getting paid until the 28th April and haven't had any income whatsoever since about 3 weeks ago, I was wondering whether or not the job center will allow me to receive allowance until after my first sign on, as I am in desperate need for some income until I first get paid.

The pharmacy where I'm working hasn't had my sign any contracts of any sort thus far, and I've only signed the apprenticeship paperwork (for the qualification and training). Not my contract for the job or anything.

Any advice on what I should be doing? Normally I get £86 a week from Job Seekers as I receive disability allowance for Bipolar, and I'm actually getting paid £6 a week less now I'm employed as the minimum wage for apprenticeships if £2.65 an hour.