Early into getting to know what each other likes, when he was domming me, he counted me down to orgasm and I loved it. He then said he'd like me to give him a countdown at some point, too.

It's been a couple of months since he said that, and that's the only thing he's said he wants to do that I haven't yet. I love to please and am very open minded, I just want to make sure I get it right. We've switched a fair bit and lately he's loving praise and calling me mummy, and I've been testing the waters with orgasm control, so it feels like the right time to introduce it.

But I'm a little nervous about it adding pressure and frustrating him if he can't cum at that exact moment? Surely there's a chance that will happen and it falls flat? Does anyone have any tips for getting it right and not leading him to disappointment/an anticlimax?

Important context, the first few times we slept together, it took him a while to finish. He would say he was about to but then 'lose it' and get annoyed with himself. I was super careful not to make a "a thing" of it or add any pressure. When he apologised and said it's frustrating I said it's not frustrating for me but I can understand why it would be for him and I don't mind at all as long as he feels good and can still enjoy it. When dominating I've also leaned more into denail and the reverse psychology of it. The more we've played and learned about each other, the easier it's gotten for him to finish. Honestly I just think he'd gotten too used to masturbating (porn, a specific toy and position, his own grip etc) and was a little nervous but we've moved past that now.