A method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE receives, on a primary cell, an activation command from a base station for activating a secondary cell between the UE and the base station. The UE receives scheduling information of a set of aperiodic TRSs. The UE receives a trigger indicating transmission of the set of aperiodic TRSs. The UE initiates a RF chain of the UE configured for the secondary cell in an interruption period. The UE receives, in response to receiving the trigger and in accordance with the scheduling information, the set of aperiodic TRSs on the secondary cell prior to receiving an initial SSB or an initial periodic TRS after the interruption period. The UE performs time and frequency tracking on the secondary cell based on the set of aperiodic TRSs.