How many days does it take to complete a withdrawal of my node (Unstaking)?

The short answer is that nobody knows exactly. There is a single withdrawal queue that will process partial and full withdrawals. Each slot (every 12 seconds) enables 16 partial withdrawals*. Validators that want to exit work have the same flow, but the number of validators that can exit the beacon chain per day rate is limited to preserve the stability of the network.
So it could take two or three days. In the event that lots of validators want to leave at the same time, it could take much longer. We don't actually know until the upgrade is complete and the network experiences a large build up of validators that want to withdraw. When large numbers of Validators withdraw from the network, the Consensus layer returns will go up to encourage Validators to stay on the network and to attract new Validators.