We waited because of banking issues. DW and I just set up our first joint account, and we've run into all sorts of issues trying to get money funneled over so that she could make a purchase. We started the process over a week ago, but ultimately it all came down to the wire (no pun).
In the end, she was able to submit a purchase for $5k yesterday morning, and I wound up doing the other $5k as a gift to her from my account1. The site seems to be pretty bogged down this morning, but I can see the pending transfer from my bank, so I'm hopeful that everything will be processed and credited appropriately.
If I understand things correctly, the gift purchase should still lock in the current rate, even if DW claims it after the deadline, right?
(1If I had known how fraught the money-transfer process was going to be, I probably would have just bought the full $10k as a gift to start with. Would have saved us both a lot of stress & frustration.)