Been growing directly in soil for 35+ years and rate it as the best method - no transplant stress and nutrients immediately.
Fresh seeds 2- 5 days, older seeds 4-7 days, anything longer than 10 days are rubbish seeds.
You must keep the soil moist the WHOLE time, any drying out for a day or two will be disastrous.
Covering the soil with shade cloth or light cotton fabric can help prevent the surface of the soil drying out, but check for the seedling emerging often (soil rising up) and remove any covering as soon as this occurs. Do not in any circumstances cover your pots with cling film or a plastic bag, this will "suffocate" your seeds and possibly lead to fungal/mould problems due to excessive humidity.
Normally, if they haven't emerged after 6 days, I am ready to plant replacement seeds.
Planting between the day after the New Moon and until the end of the first quarter of the lunar cycle, can help with germination and is a method I swear by for 25+ years.
Hope this helps,........
Organoman.