Petition approved but waiting for a visa

So here’s my problem:

I am an American citizen married to an English citizen. We’re in England for the summer. I’ve filed a I-130, which has been approved.

Now the petition is with the National Visa Center. I have to go back to the US on September 1st, and my husband actually has a ticket for the same day, roundtrip returning to England within the 90 days allotted by the Visa Waiver Program, which we bought a while ago. I haven’t yet received the bill to pay the visa fee, so I’m imagining it will take some time.

So my question is: is it worth risking him coming with my on the 1st? He’d return to the UK—we’re painstakingly doing everything legally, which is why we’re doing it here and not when we get to the US. We were living in France before this.

For personal reasons way beyond the usual (the death of a child), we would prefer not to be apart right now.

Any advice?