Methods, systems, and devices for wireless communications are described. The method includes receiving, via a control channel, an order message instructing the UE to perform a random access channel (RACH) procedure, and selecting to perform a first RACH procedure or a second RACH procedure based on a preamble preparation time gap between the order message and a first occasion for transmitting a RACH preamble, or a payload preparation time gap between the order message and an occasion for transmitting a RACH payload, or both.