depends on where you are in Thailand You can apply for the 30 days extension 7 to 45 days before your first 60 days end Depends on the immigration office Takes usually approx 1-2 houres and costs 1.900 thb
If you have a dutch passport, no need to apply for visa You get 60 days visa free which you can extend at local immigration for another 30 days A visa will give you same period
why you keep repeating this when its totally wrong ?? Don't give false information if you don't know what you're talking about please Untill today 30 days and now "rumours" go around that it will be MAYBE effective in September not June anyway