If you really want to know... They mess around a little before, but what would count as a real first time happens after ML is mostly sane most of the time... So not what you're imaging. Worse lol. Because his mind mostly heals but like he said he's technically no longer human, more like
SPOILER SPOILER SPOILER SPOILER SPOILER SPOILER SPOILER SPOILER
an Eldritch abomination, and he's... Not in his human form that first time. He's a sweet, protective and green flag Eldritch abomination, funnily enough. An Eldritch abomination and yet a whole green forest. Surprisingly respectful too (yandere, but the overprotective kind and because he has reasons, not the "mine or no one's" type)
I'm afraid you'll have to wait for quite a long time, it happens halfway through the novel, it's slow burn lol But very much worth it, they need to get to connect first after all. And they have a couple more explicit scenes afterwards as well. Romantic scenes on the other hand they have plenty, and plot will be plotting, along with a lovable cast beside them.

My perverted self talking here but i need a chapter of MC having sex with ML crazy version.