I wish it was first come first serve.. But in the stockmarket it is random.. I have often been the first one bidding at a price point and still didnt get a fill first.. and then I have often added my bid to a huge bunch of orders and then got my shares seconds later, before everyone else.. totally random... So I would expect that it works the same for coins..
RE: Bitcoin at all time highs, whats gonna happen? and let's look at Small Account Building trades