O̶u̶t̶ Indoor Winter Autogrow :p

If all is well, in 2-4 days, 6 days maximum. If nothing after 7 days, plant new seeds. Make sure to leave the seed pot/container uncovered they need good air exchange for germination, any type of cover will reduce air exchange. Also, never use a "humidity dome", this also reduces air exchange, but can also increase the risk of moulds or fungus attacking your seed(s). Hope this helps,........... Organoman.

If you have some microscope/magnifier check the trichomes. Most of the trichomes should be milky/cloudy. 30-50% should have started to change color into amber/brown. if not, 70-90% of pistils should have darkened.

Aside from phosphorus some things I can think of are potassium, molybdenum, heat, internal energy (sugars). Now, a lot of things can affect that. You have cold temps. So, that's the main thing. I've grown many plants in winter/cold. They obviously purple more. If you can boost the heat, phosphorus uptake will be better and it'll flower better. I'd recommend sugars, mulch, and even some sort of cover for the pot. OH, and importantly, less nitrogen. I can guarantee you that was mostly heat as the main factor though, because low heat also means little growth. And that plant has exactly the sort of symptoms I've seen hundreds of times in cold. A larger pot would've helped enormously (though obviously too late for that). Because the temperatures are then significantly higher for the roots, meaning it takes up nutrients and water better and it has more capacity as well as more nutrient availability and space. So in the future, keep that in mind.

If shes an auto changing the light cycle won't effect her at all. She's already flowering means you just have to be patient. For autos more light equals more bud. Don't forget that. There is no point changing now because she's doing just fine just a bit slow mate don't worry to much. My sour ds autos have been in around 15 weeks. Lol and still not fully developed. Happy growth be patient.