No problem. You also want your tank to mature a little before adding an achilies. Not to say it cant be done, but to a certain extent, the biology booms and busts in a newer aquarium.
My achilies was a karma gift. I spent ALL weekend moving a club members tank. I ordered an achilies online on monday. Tuesday they sent me an email saying "sorry..mistake on our end, we dont have it". I was crushed, "fine, just refund my money". 4 hours later.. knock knock.. next day air pacakge for Brian. Huh? Boom, free achilies.