Yes, try it before cutting the stem. Ride at least a month like that first to make sure you're not going to develop some fit issues. After that, if it is a star nut you can tap it down a little more (be careful, you can't pull it back up) and cut the excess material off the top of the steerer (also be careful, measure twice, cut once) to take the extra spacers off.

As for the extra spacer on top recommendation above, I don't think that's very important with metal steerers. It's more crucial with carbon ones... which should be using a compression plug and not a star nut anyway.