If he doesn't tack on I'd leave his BT at 7.30pm and assume he doesn't need the longer nap. Mine was never able to extend night sleep in the morning hours but could with an EBT, maybe yours will be the other way around and add wake a little later.
With dinner at 5.00 I would do a solid snack (small one) and milk drink at about 6.30pm, I called it supper and DS didn't blink an eye at it's sudden introduction. Sometimes if dinner was a little late or we were eating for longer and if he needed an EBT supper came directly after dinner which sounds crazy but he still took it, a bit of solids and a bit of milk. We did it downstairs at the dinner table as it wasn't cuddle time. Then up for teeth, bath, pjs, cuddle, then bed. He doesn't *have to* have a supper, it's just offering it, the point is weaning the BT bottle of milk and creating a new routine isn't it?