Huh, I thought I had commented on this thread before but I guess not. I seem to be one of the few that got their salvia plants to flower as well. I had a beast of a mother plant that I was taking cuttings from which I eventually just let grow out. She must be 1.5-2 feet tall and is branching out like crazy due to all the supercropping/cutting taking.
Anyways, I have her growing under florescent lights and during the winter at one point she was only getting 5-8 hours of light max a day. She started getting those tell-tale signs of flowering so I kept her at those light hours. I do not think age is a factor which plays into flowering. I really think uninterrupted hours of darkness is the defining factor. (14+ hours of pure darkness being needed).
Temperature may play a secondary role, mind you I'm only speculating on this. The temperature in my house can drop pretty low in winter due to inadequate heating and just the fact that it's an old house and doesn't hold heat all that well. I'd say it dropped no lower than 55F, but probably hung closer to 65F during most of the winter.
So anyway, the mother plant flowered and I must have gotten 10-20 or so pods of the plant. Each pod had 4 seeds iirc. The flower would stick out it's style(the white part that catches pollen I presume), and fall off within a day or two max and leave the bottom part; the seed pod, on the plant. The seed pod would take no more than a day to fall off and only several hours to dry out most of the way.
So in the excitement, I started planting the pods at all stages of development. I planted them before they fell of the plant and after, and before they dried out and after. I had never thought to put some in a bag and let them sit for a while before planting. I just presumed they lost viability very quickly like caapi or iboga.
All the while, my coleus was flowering at the same time. So I got the idea to try and make a salvia-coleus cross in the hope that since they were from the same family that they'd at least make a sterile hybrid. No luck though. I think what actually happened is that the one 'seed' that actually did sprout was just a coleus seed that found it's way into where I was planting the salvia seeds.
Fast forward to today, the seeds have been sitting in moist moss for months now. I was looking at your pictures, and the seedlings you have happen to look identical to the ones sprouting out of where I planted the salvia seeds. They didn't sprout until this past month. So here's to hoping that they're salvia seedlings.