Do I need to send proof that the mark is being used?

Yes. You will need to send proof that the mark is being used in this country.

Acceptable proofs of use could include: a page from a web site, an advertisement, a brochure or a pamphlet which describes the product/service and shows the trademark.

Labels, tags, or packaging are also considered acceptable proof of use for a trademark.

We do encourage you to plan ahead when filing and sending papers and not wait until the last minute.
All forms when received are time/date stamped, according to Eastern Standard Time (EST) and EST controls for purposes of determining the timeliness of a document. Any submission that arrives as of 11:59 p.m. EST will be given that day’s filing date (i.e., regardless of the PTO “normal” business hours).