During your move, you will never be without electricity or gas. The grid operator will never disconnect your supply without reason. There is always electricity and gas available in the home—even if you haven’t yet applied for energy. The grid operator continues to supply energy until a new supplier is registered. So, you will never suddenly be without electricity or gas.
Of course, you shouldn’t wait too long to find a new energy supplier because there is a chance you could be disconnected. You will have to pay for the electricity and gas you use between contracts. Make sure you never have a period without an active supply from your supplier.
If you move to a home without a connection, you will first need to apply for a new connection with the grid operator. This can take some time, so plan accordingly. In practice, this is very rare.