It depends on how large your water heater tank is but it can take at minimum 1 hour and up to 2 hours to have hot water again in your water heater once all the hot water in the water heater is used up.
A gas water heater will heat water faster than an electric water heater too so you could see hot water sooner with a larger tank gas water heater than you would with an electric water heater with the same size tank.