Methods, systems, and devices for wireless communications are described in which uplink timelines may be reduced by initiating, at a user equipment (UE), uplink transmission processing prior to receipt of an uplink grant for an uplink communication. A UE may identify one or more uplink transmission parameters associated with a reduced uplink transmission timeline for an uplink communication, and use the uplink transmission parameters to initiate processing of the uplink communication prior to receiving an uplink grant from a base station. The uplink transmission parameters may allow for packet preparation at a higher layers (e.g., at a medium access control (MAC) layer or radio link control (RLC) layer) to be started or completed prior to receipt of the uplink grant.