@Hanna2104
You can not transfer excisting reservations to your account. The are made on the account of the current host. It means they have to be cancelled (penalties applies) and guest can rebook with you (if they want).
Alternative:
If current host agrees, you could act as a co-host for those reservations to manage them, but ofcourse then there is a risk for the current host (not being the owner of the property anymore)
You can start creating new listings on your own account and even publish them, but maybe wait to accept reservations when the deal is finished (keep clalender closed)