No. You add feats when you gain levels; you can't save them for later.
This is honestly exactly what the "BAB +1" requirements are for.
You could play half elf. There is an option, ancestral arms, that lets you switch out your skill focus for a martial or exotic weapon proficiency.
A bit of a restricting answer, but it is not a bad option, I suppose, since it is a core race, thus no one really will complain, and it has a +2 you can place anywhere you want. I'm sure there are a lot of other little advantages that it would help, can't be bothered to look. Might give a good bit of back story. Say your elf parent used them (funnier option would be to have your character think their elf father was a warrior that used them, trained until they mastered the weapon, then find out that the father was a different elf entirely. Might just be me though. Too tired, bad humor showing)