expert opinion asked ? Maturity in day 49 flower from 60-65 (according to breeder)

I'm far from expert, firstly its good to know you got the right Date to start, flowering period starts when you see the first sign of flower, I nor ally use the stigma as my tell. Often people use the day that they switch light schedule but sometimes this can take 3-4-5 days to show which can skew the "days". Time is a man made concept used to track how fast atoms decay. Nature knows no time, only cycles. How much a plant gets dome within those cycles is determined by many things. A general rule of thumb. Higher levels of radiation will always lead to accelerated cycles with same "time frame". Trust your gut. Terpene peak is precisely 2 weeks prior to thc peak that we all use as a metric for harvest. A good little trick I use is the brightly colored yellow stigmas. As buds develop the stigma slowly turn a lovely orange. As flowering progresses the ratio of bright yellow stigma will decline until there is no more. This gives a good indication of how much more buds development will happen. Once I get to 80-90% orange I do my trichome sweep at multiple points across the plant and harvest if she says so.