Sorry you're feeling anxious.
Definitely waiting is better - at 5 weeks the odds are you'd see nothing, which would be so upsetting (and perhaps unnecessarily so). My clinic (I only conceived with IVF) does the early scan at 8 weeks to be sure that they'll see a heartbeat if it's viable. Prior to that you just can't be sure so you'd have to come back again if you didn't find it anyway.
Do you *need* to do the scan? I skipped most scans 2nd time round and ended up much more relaxed. It's a false reassurance when you go from one scan to the next, because you only feely relieved for a day or so, then the anxiety begins building again in anticipation of the next scan, and so on.
Hope all goes smoothly for you.