I'm sure that the timing is relative to a lot of factors we can't predict. Some of the autos I've done before came in right on time and others have taken 2-3 weeks longer....personally I think you should anticipate them taking 1-2 weeks longer than the average time to maturity documented by the breeder. I just finished three different strains, none were autos this time and only one was feminized but they were all different_ the ones that should have been ready first took almost 3 weeks longer, the one that was suppose to take the longest was ready first and the third was less than a week more than advertised. Unless you've grown the same strain/ phenotype before you can only go with the flow, watch the trichomes and take it from there. Just keep a good watch on them_ one of the pants I just harvested went from 5% amber to 20% amber in just two days_ so it came down the next morning. Cheers!
Oh, and when I've trained autos by toping once and then using LST and or super cropping the flowering has started on time (about 4 weeks) but they took at least a week longer to mature....more like two weeks...