Bitcoin Core version 0.21.0 is now available for download. As described in detail in the release notes, miner block templates produced by this version of Bitcoin Core will signal readiness to enforce taproot during the roughly three month period specified by BIP341.
If, during that time, 90% of blocks within a 2,016 retarget period signal readiness, taproot will be locked in and this version of Bitcoin Core will begin enforcing the additional consensus rules specified in BIPs 341 and 342 at block 709,632, which is expected in early or mid November.
If miners don’t lock in taproot by the end of the three month signaling period, a separate attempt to activate it using another mechanism is expected to be tried. The activation mechanism has been designed so that, by roughly mid August, it will either provide us with an assurance that we’ll soon have taproot or immediately give us valuable information that users and developers can use to make the next activation attempt more likely to succeed.