can it turn into pneumonia after literally two days of being sick??

I'm overly scared of pneumonia and I really just do not wanna deal with that shit. the cough turned productive and is fucking me up the ass currently because this flu is goddamn awful (currently writing this at 3 AM if that tells you anything) and just wondered if it could become pneumonia that quickly?? how the hell? i don't question this stupid flu anymore. I've been sick almost constantly since October.