Just a suggestion: You get a lot of baby onions in onion sets, so I'd suggest planting them maybe 10-15 each week for several weeks. That way, they won't all be ready at the same time.
DH planted most of an onion set several months ago, and now they're all bigger than scallion or green onion-size, but not as big as full-size onions. They're about the size of 3-4 scallions. They still work fine, and DH likes them raw, so he'll eat what I don't need for a recipe (I can't stand raw onions), so they don't go to waste. Just thought I'd mention it.