It's an interesting one whether it should be in the morning or primetime. It works for both slots really.
In the interests of the name of the show and the 9:25 on the clock of the opening titles I think it should be in the morning. I think that's what Ant and Dec would want too.
More than likely it'd be a primetime slot. I can't imagine they'd stick 2 of ITV's biggest names on a Saturday morning slot that is now really graveyard viewing compared to what it was like when it actually aired. Got more chance of it rating well in a good slot. Perhaps if it does happen, they could do it at 9:25 in the evening.
I'd still like to see a reunion episode, would be fun to see what some of the characters from the sketches are up to now. Shame they're knocking down The London Studios as it won't come from the same studios - but I guess Tiswas Reunited didn't and nobody seem to be bothered!