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.