Going all in preflop early in a tournament is always risky and best to avoid it when you can. If someone at my table is doing it a lot, I like to wait for someone else to take them to a showdown to see what they had. Other than that, early on I'm only going to call when I have QQ, KK, AA or AK. If they're shoving all in every other hand and noone else has knocked them down yet I might call with AQ , AJ , A 10 or JJ. Best to be patient, if they are consistently shoving with weak hands, they won't be around long.