I would like to know if I can start doing these days before the simulation course, and if these days (obtained before simulation course) count to obtain the DP final Certificate.
If you’re asking if you can count watchkeeping days earned before the advanced class then yes, the only requirement is that you have at least 30 days after your advanced class before submitting your time for your certificate. You could take basic class, do 180 days, take advanced class, do 30 more, then submit your application to the NI. If you take basic, do 250 days, then take advanced, you’ll still need 30 more days.