Where I work, the F/O sets power but removes his hand from the throttles prior to 80 kts. The captain puts his hand on the throttles at 80 kts, because
only the captain makes the decision to abort and the execution of the abort. The call is according to SOP (Stop, abort, reject). At or just before V1 the captain removes his hand from the throttles, and that is the cue for a "go" decision.
