When to have best man stand at altar?

So our ceremony will be outside under a bridge and I am trying to figure out the placement for the best man. I like the idea of having the groom and best man already at the altar rather than walking down the aisle. However, I need someone to walk my mom and stepmom down the aisle. So my fiance will walk them both down separately and then take his place at the altar. My question is whether or not it would be weird to have the best man just standing up at the altar during this time alone. I feel like it would be weird, but I like the idea of my maid of honor walking alone as the last one to go out before me and my dad. Because it is outside there is not a room he could just hang out in and then pop out after my fiance takes his place at the altar. Has anyone done something like this before and could offer suggestions?