I think I've become a very big fan of heated seed mats and covered flats. I planted the celery and onions last Saturday.
Celery "days to emergence" is said to be 10-20 days. I already got tiny little sprouts yesterday!
Similarly, many of the onions were up by Wednesday, even though their germination time is supposed to be 6-12 days.
This gives me high hopes that I'll have decent sized seedlings for transplant to larger containers by the time I want to reuse the flat at the end of the month for the next starts. Yay!
Still too small to get decent pictures, but soon.