You may be able to assert “use analogous to trademark
use” to claim priority over someone else who actually made
technical use of a confusingly similar trademark or service mark
before you did.
Technical Use
For a U.S. registration, an applicant
(who is not relying on international rights) must have made
a bona fide use of a mark in commerce in the
ordinary course of trade. A U.S. applicant cannot seek to
merely reserve a right in a mark. Such technical
“use” means:
Trademark Use. (1) A term or other source
designation placed in any manner on the goods or their containers
or on the displays associated with them or on the tags or labels
affixed to them (or if the nature of the goods makes such placement
impracticable, then on documents associated with the goods or their
sale), and (2) the goods are transported in commerce.