Eh, well, depends what kind of trichomes u are talking about.
If you are taking about the pre flower, (bud formings) you will see them fairly early in most cases.
But if you talking about sugar leafs & trichomes to the eye.
Well, it really does depend on the strain.
My strawberry gorilla started early. As did my banana purple punch under my SF light but didn't see it as early as in the 1 under my p1000. Much denser buds.
And on my kosher I am actually only starting to c heavy frosting now. And that is the case with most koshers I've checked.
Does depend on the strain and your spec of light. And just straight genes of that seed.
Good luck she should get frosty thru sub ripe and after.
Good luck