Student job without matriculation

Hallo Leute. How much trouble would I be in if I applied and started working a job without matriculation. It's a simple job, that I was supposed to get as a student job, but I haven't enrolled for school yet (initially admitted for Jan intake but deferred to April). Apparently, as per what I presume is bad advise) I can get an enrollment certificate made and start working as no one really checks up on it unless something has happened, but my conscience tells me it could land me in trouble if the authorities know about it. Also skeptical about potentially getting my employment agency into trouble with the law. What's the best way to approach this? Contract had already been drafted and due to start in a few days - should I just come clean and ask them to consider me once I have been enrolled or just risk it? Is deportation a potential outcome? No harsh judgments please

EDIT: Problem solved, advise was extremely helpful. You guys are awesome and your country is too 🤟.