I've been doing it for months. Drain, then dose for the volume of the tank, then you can refil immediately ti prime will disburse and do it's job, I've never had any issue.
if it's more than a 50%
water change. I dose for the entire volume of the tank.
if it's a half or less water change, I dose for that volume instead to save some of the prime..
I have a 50 ft hose and drain it outside to the yard. then I run it around the side of the house to the outside faucet, hook it up to refil the tank, both take a while to accomplish, but it's much faster than a short siphon and buckets for sure, and no waste going down the drain and so much easier.
just pull up a chair pour a drink, water the plants, and monitor so that if something goes wrong, like it flopping out of the tank or gets close to the top, you have your eye on it.
and do the last couple gallons by hand so you don't risk
overflow
turned a two hour mission with lifting and back and forths to a half hour or so of mostly sitting around enjoying a drink. Much more fun the less involved it is to do it.
DON'T "prime later". it's a big nono, prime before filling and follow the standard dose instructions, it will be concentrated at first, like a double or triple or more dose depending on the size of the water change and dilute as it fills. the fish will handle it fine, but chlorinated water can kill your cycle if you do it after especially on a big water change.
I know plenty of people will claim, "nothing happened to my cycle and I do yada yada" but if chlorine wasn't effective at killing bacteria they wouldn't use it for water treatment, so always be mindful to do it in the right order to avoid it crashing on you.