Don
We started last year and as we had to wait for our poly tunnel I invested in the grow lights. We had them about 40-60 cm above the seedlings. Then got a cheap timer to control how long they were on for, I tended to time it for 10-12 hours, as I think that that mirrors what we get in March (( up to the equinox) when we are sowing seeds for light. It did work for most seeds we tried, not parsley though!! and the seedlings were not so leggy. Hope it works for you.
Ali