I don't think there's a right answer, though I do think telling is always better than being discovered.
I told my wife about a year into our dating, and I think that was probably too long. And to be honest I think I did it in such a clumsy and awkward way I didn't win myself any points either. :P That being said, she was enthusiastic at first, then started having reservations, and it was something we struggled with for many year and only recently are coming to a place where it feels like we're doing ok. An important piece to remember is that however she takes it, it'll ultimately be a process as it'll shift how she relates to you to a certain degree. You haven't really mentioned if you think she'd be open to this type of thing. Does it feel like she'd be ok with you dressing? Do you know what you're asking of her? As in are you hoping to involve her in the dressing? Do you want to dress at home regularly? Is it ok if she doesn't want to be involved? I'm sure you'll get it figured out and I wish you the best of luck.
No real answers (sorry for that!) but a big hug and a friend;y shoulder to lean on if you need it in the future. Happy New Year!
Hugs,
Raeleen