Under Speedy Trial, miners would have three months to signal support for Taproot after its code is shipped through Bitcoin Core, Bitcoin’s primary software version. If 90% of the blocks in a given time frame are not Taproot-supporting, then that means miners don’t support the upgrade and activation fails. If the threshold is reached, then activation takes place after a six-month “locked-in” period. During this time frame, the upgrade is in the bag, but its actual activation is delayed to make sure there are no hiccups.