puprles come out at end, if you get them... not all 'purple' strain offspring will have it. May need a pheno-hunt to get one from the seeds you have.
it takes forever and a day... don't think about it. only watch teh triches all over.. pick different spots -- top and below a bit where you still care about teh nugs -- not so low you look at fluff and popcorn nugs.
When it happens, in my experience it happens quickly.. once you see amber everywhere -- not just 1 lone trichome here and there, but still few and far between overall -- i think it's a good indicator it's about to hit the window of harvest. could be wrong.. that sort of familiarity i am stil building up myself. just keep observing.. take notes the first couple times and it'll burn into memory for future.