Pathfinder: early animal companion for rangers

[stack]

In a PBP pathfinder campaign I'm DMing soon, I have a request to allow rangers to get an animal companion at level 1. What is a fair trade off for this? The minimum I assume is requiring the boon companion feat. Should spellcasting or favored terrain be taken as well? If it helps, it is specifically for a mounted archer.

[kharmakazy]

I don't think it's OP to let him just have the thing early. Rangers get the short end of the stick even in PF. (not the SHORTEST end of the stick, but it aint tall)

[MeeposFire]

It doesn't really make too much of a difference. A feat would be more than enough. Give it a cool name and have the animal be given at level 1.

[Rixx]

I'd say a feat that gives you your companion early would be fine, though giving it some secondary effect would probably be good so that the feat continues to be useful after the ranger would normally get his companion.

[rokurei]

The Advanced Player's Guide has a variant for this I think... hold on, I'm gonna look it up.

EDIT: Nevermind.
EDIT Again: http://www.wizards.com/default.asp?x=dnd/re/20031118a

Not an animal companion, but might help you out - the companion is less powerful than a druid animal companion by 20.

[stack]

Boon companion would bring effective druid level up to ranger level regardless, but normally you can't take it before you get a companion. (Some might argue that it wouldn't help a pure class ranger, but it does in this game regardless).

I was wary of giving a full blown companion too early, but if he played a druid he could have the same thing. Plus it will be used as a horse for a mounted archer, so I guess I'm not worried about giving an extra set of attacks.

So the consensus is that no other penalty is required?