Bud Give or take an Hour???,, Flowering need's to be Dark not, 13 hours light today, 8 hours light tommorow,, all that will happen by doing this is your plants will stress a little and worse of all will take longer too flower. Trust me ive done it. the first plants i ever grew where like that in a closet like affair but it had no fixed door so lots of light leaks into the space hench i was flowering for like 11 12 weeks it s not worth it i ended up with some moldy smoke too had to destroy two tops from three plants.....it all adds up...
aldo the mold was probly due to humidity id say my fking around with the light s just made it worse because they were going too long ,it didnt help that there was lots of skunk in the plant so they naturaly needed more time but i fked up is what im saying 12/12 means 12/12 no light for 12 hours other wise the plats take longer to finish.....
Good luck with the new plant i hope its got no bugs ,draw back with bringing plants from the out doors is it could be carrying little fker's.....

Well Keep it green ,Peace D