Every holder of a new trademark has the right to claim the priority of its trademark abroad. This right exists during six months after filing the trademark. The trademark application abroad will then be protected as of the date of the filing of the first application. This gives the holder of a trademark a powerful weapon.
Time and information
As priority can be claimed, you do not have to make your decision where to file your trademark immediately. So, you first await the registration of your trademark (and see whether parties have objected against your trademark) and of course await the reaction of the consumer on your new trademark. In the event your trademark is successful, you can determine which countries are important to you.