The time is the total time in flower.
Whether you flush or not is up to you, and is not given as flower time plus flush time.
If it says 63 days flowering, that means you would need to start a 10 day flush at day 53, hypothetically.
Unfortunately plants can not read or follow the instructions on the packet, and the suggested times given by the breeders are at best, fanciful and only intended as a rough estimate. There are so many variables when growing which all effect flowering times, such as light intensity, nutrition, temperatures, topping/training, grower skill, growing techniques, plant genetics/phenotype etc, that giving an exact time is impossible. Comparing just lights - a 1000 watt HID light is going to produce vastly different results than a cheap 32 watt blurple light. If you look through other peoples diaries, you will soon realise that many strains quoted at 8-9 weeks flowering are actually taking 12 weeks plus, mostly due to the infinite variables. Growing photoperiod plants outdoors is far more predictable, but most breeders are sensible enough to give times as "mid to late September" or "end of October" and are generally quite accurate. When it comes to autoflowering plants, the times are even more fanciful and the breeders are really not doing themselves any favours by giving totally, real world, unrealistic time frames. Most say their strains will take X amount of weeks, but generally whatever they tell you, add 4 weeks on top of what they say, just to be safe. Again, it comes down to all those variables, but the competition to be faster than your opposition has many breeders claiming unrealistic times, just as a marketing spiel and has very little bearing on reality.
Hope this helps,........
Organoman.