Yes she knows from the beginning. The guy himself never told her but she says she could tell because he's so obvious, it's only the mom who's really dense and couldn't figure it out.
She will likely say so by the end of chapter 2 as well, if the adaptation follows the LN. This is really early on in the story.
The rule of thumb is half your age plus seven, right? 30/2+7 = 22, and he's 20. It's really not that far off. In four years, it'll be 34/2+7 = 24 and he'll be 24. They're both adults, might as well just start now.
Thanks for the translation, but you guys seriously need to read over your work or if you're ESL, get someone to proofread. It's almost illegible in some parts.
@Mfrost This one's probably mostly on me. I didn't realize 2.1 even came out until last night. Too distracted by Genshin I guess... Our 2.1 will be out soon.
Edit: @Nosebleed Couldn't resist clicking the spoiler, heh. Nice to know it was what I thought though. I had a little bet going with lightning.
@Mfrost we never saw this coming, but we will use all power to release the chap2.1 and 2.2 as fast as we can, good quality translation and what else you
can expectt 'a blue page' too.