lol, that's complicated. But the AZ vaccine wasn't originally intended to be a 2-shot process; like J&J, people were supposed to get just one. Then in the States, there was a production error that resulted in a lot of vials being thrown out. There were also some side effects that, while not statistically significant, put some people off. So the AZ vaccine isn't being used here.
However, people involved in vaccine testing have been trying a mix-and-match approach involving Pfizer, Moderna, J&J, and, I think, AZ. And in terms of producing good levels of antibodies, that seems to work well.
So just relax and enjoy it. If the delta variant turns out to be bad enough that we need additional booster shots in the fall or early winter, they'll let us know.
I had the Moderna shots; the pharmacies prefer it to Pfizer because it doesn't require the kind of extreme refrigeration Pfizer does. Though it's a "bigger" shot, literally: the dose is three times as large as the Pfizer dose, which some people think is why some people had longer-lasting "flu-like symptoms" after taking it. I did, but feeling shitty for a couple of days isn't all that dramatic.
So if you're going to have a reaction from your Moderna shot--have you already had it, like today?--you may begin to feel the effects eight to 12 hours later. But you'll survive.