Specific Flower Periods

So I am aware that most indica strains will take about 8 weeks, where as sativas will take much longer some to 14 weeks I hear. But my question is more specific than that. I am looking for a more dialed flowering period for the strains Space Needle, Captain Kush, and Purple Kush if possible. I have looked online with no luck. However I see most breeders or seed banks give out day ranges for their products. Any help would be much appreciated thank you!

Go by the Trichomes.
Get a scope or loop.

Unless you are growing from a clone, and the person you got the clone from is fairly experienced with the strain, you cant get a specific flowering time to the day. You're going to have to do it the old fashioned way by looking at the tricomes and watching the hairs turn from white to red. Also you have to remember that when breeders give out the range for the plants to be finished they are usually running pretty optimal conditions because thats what they do for a living. If your plant is going through any extra stress such as low light or over heating you might not be able to follow their guides at all

just look at the plant when you think its done....add 2 more weeks