if the embassy knows your flight date they will ask you to show them a ticket to Thailand at a later date. If you can't provide that your application will be refused
If you put a travel date to Thailand in your application that is already passed they will ask you to show a plane ticket to Thailand at a later date or refuse your application
Anonymous participant 506 pas si vous faites la demande à l'ambassade de Thaïlande en France. J'ai juste eu a fournir la lettre de description de mon activité en anglais. Tout le reste: relevés de compte, Kbis, relevé INSEE etc en français
Do not listen to people telling you to travel and do a border run once your visa is approved. If you put your travel date on the 17th in your application and the visa is not approved yet they will ask for a flight ticket at a later date. If you already flew and cannot provide it they will refuse your application