I have been doing this a while (since 2019) - and it ALWAYS pays to buy as much kit as you possible can at once. The value of Fly More is less a value than it once was, but still, add the price of batteries bought afterwards alone and its...
It depends on your budget and specific needs, which we have no way of knowing. If you are serious about photography though, are you willing to miss a shot because you ran out of battery power? At a minimum, I would recommend the fly more package.