I think it depends on the project. If you've raised money then you should always file the trademark as soon as you're settled on a name. If it's a little side p

I think it depends on the project. If you've raised money then you should always file the trademark as soon as you're settled on a name. If it's a little side project that might get abandoned then it's probably not worth the expense. The other consideration is how important the name is. If you think it would be a really big deal to change names (in the worst case) then it might also be worth it. What you should do in any case is check for existing trademarks. You don't want to name your product something that you won't be able to own the trademark for.