It always depends on the bank where you do the main financing, they take into account their own processing times + buffer. because they themselves have to apply to the KfW by 31.01.
so for most banks the deadlines expired on 14.01.2022, currently only a few Sparkassen, Sparda banks, and Volksbanken still offer the KfW-55 loan, but their deadlines will also expire in the next few days.
if everything is too tight, then rather finance everything through the house bank instead of the KfW loan + take the grant from the KfW.