when do I test?

My periods are weird and I haven't had one in awhile. I also don't know if/when I ovulated. So I don't know when to test for pregnancy do I just keep waiting or do I take one now and risk it being too early. If I test now I'll have to wait to test for another week or two when I get more tests...
Update: I think I'll either test tomorrow morning or Christmas Morning. Maybe I'll have an extra gift this Christmas. Still trying to not get my hopes up though.