Hello @Kriskum and welcome back to the Wefugees Community!
My experiences and observations regarding the transition from the residence permit according to section 104c to the one according to 25b are still very limited since this legal process was introduced relatively recently. As far as I understand, however, you should receive the 25b immediately if you do meet the requirements. I think for people who do not fulfill all conditions, it is also unlikely that the immigration office will issue a "Fiktionsbescheinigung" (which would be an adcantage in case people need just a bit more time to meet the requirements). I will link my colleague dear @mbeon-Éanna here.
Maybe he can correct me or add information.
All the best,
Meike