Poultry Talk Ontario (pto.ca)

I have not done this for so many years I am looking for some input.
The shelves are in South facing location and I have an IKEA lamp with 60W light bulb in it.

Keeping in mind I am only using what is in the house and not planning to purchase new,
Do I use the lamp and if yes, when and how many hours ?

I don't know if this will help you or not, but here goes ...
I don't have have my plant rack right next to a window, but I use 6000 Lumens T5 LED lamps underneath two of the shelves. They use 20W, so lower power but brighter light than a regular LED shop light. I turn them on when I sit down to work at 7:30 AM, and turn them off at around 9:30 PM. Since you have yours located directly by a window, I think you can probably get away with not having your light on as long. Maybe on at sunrise and off a little after sundown?

I didn't bother with a lamp. Just stuck 'em near a window and off they went. In fact I think I got better results than when I used a GROLAMP, no aetiolation!

Bottom heat will do way more than overhead light. Plastic humidity cover to keep soil moist. Having said that, they will germinate if you don't add heat or light but it will take an extra week or more.

The shelves are over a heat register, not sure if it will make any difference.
I don't really care how long they take to germinate, somewhat worried about the temperature of 21C needed, since this house is 17C overnight and I have no intention heating the seedlings.
I think it's going to be tough love here, since it looks like a cool summer, they start as they will grow, or not :)

I wouldn't worry our house is the same temperature. My shelf i over a baseboard. There is a pic of how well they've done in this post
Garden Diaries, 2020
I have repotted even more and they look good.

I'm far from an expert on this subject. First year for me starting everything from seed. I AM HOOKED! I have really enjoyed this. So much so that I've already put requests in for hubby to watch for some led units for me. I am using T5 plant/aquarium tubes currently. I dont think its the best but it's what I've got and seems to be working ok.
I agree with @LongCrow about the bottom heat. I used my unused brooder plate. If you could (safely) tent your trays over that heat register and just adjust the airflow until you get a good temp it will speed them up. I tried both with and without heat and the difference in time AND germination rate was fairly significant. I currently have tomatoes EVERYWHERE. Over 50 . I just couldn't stop. We will grow somewhere between 20 and 30. The rest are going to a community garden being planted by Canadian Mental Health in Barrie. My sister-in-law works there so I was glad to donate them to a good cause.

Below is the set-up the DH made and has used for the past 4 yrs. - a fluorescent tube on for about 12 hours a day or longer. For some plants, he put a heating pad under them.

i used to use heat mats and then got lazy. its tough love here for sure. but i have a small greenhouse and a heater in the greenhouse now. lol. i started plants and have had a garden since i was old enough to play in the dirt pretty much. a good south or west facing window and decent watering habits is all you really need. the trick is ro keep everything short and bushy. do not allow the seedlings to get long and leggy. tomatoes are bad for that...you want them short and compact while making roots. i found supplemental light definitely helpful for those of cloudy days. i just used a shop light put down almost touching them. a very bright window with 14 hours of light will do though. yep seed starting is fun. i love watching things grow and fussing and planting things on. just whatever you do-there are things better started very close to planting time-like pumpkins lol. they will take over very fast....lol i do it every year and they sprout in 48 hours and grow like crazy!! lol

Thank you for all the input, while I was still trying to decide to light or not to light, Mother Nature was doing it's thing, unencumbered be my helpful hand and 3 days later, Mesclun and kohlrabis are lifting their heads, considering I planted them in a mix of well aged chicken compost and some old potting soil from couple of plants that have died long time ago, I would say it's a pretty good outcome