You can submit your extension no earlier than 14 days before your visa expires. We recommend applying about 10 days before, but it's still possible later, even on the day your visa expires.
It makes no difference when you apply: the 30 additional days are always added to your original 30 days. You can book with us at any time; we'll start the process automatically as soon as the 14-day window opens.
Please note that if you are very short in time, we might not be able to help.