I think you can only have 5 Spirit Wolves (I think more I dunno) and only 2 Dire Wolves so Pre Buffing wouldn't really matter unless your going for higher stats, But yeah you can prebuff them.
Maximum number of a summon type, and the skill lvl required to have that many:
5 ravens are max, slvl 5+
5 spirit wolves are max, slvl5+
3 dire wolves are max, slvl3+
1 grizzly is max, slvl1+