There's more to it dudeabides.
You cannot run for president as a serious candidate without equally serious fundraising and organisation. The longer he waits, the greater the risk that loses all of those people and is reliant on another established candidate collapsing.
Not to mention getting on the ballot in primary states - something which I'm pretty sure can only be done after one has declared their candidacy.
Arkansas has the first deadline of Nov. 9. Now, maybe it's not a big deal if he doesn't compete for 32 delegates in a state Hillary lived in for a quarter century. But I think he'd want to get in by the following day, the deadline to compete for Texas' 208 delegates.