Very tiny triggers can be tough to keep alive. For them to thrive you have to feed them several times a day (like 4 or 5). If you feed just once a day or every other day like you can with adults, they'll starve.
The other thing to keep in mind is that tiny triggers don't take long to become much bigger triggers, so you want to make sure you already have a place to put an adult ("planned" upgrades don't count, because they usually don't happen).
Dave