Note: This question does not apply to I3C Basic v1.0 and I3C v1.1.
In I3C v1.0, an I3C Target was required to wait 1 ms (i.e., the tIDLE minimum value) before it could send a Hot-Join Request. Newer versions of the I3C specification define a new tIDLE minimum value of 200 µs, since that is sufficient for all valid uses. I3C v1.0 devices may choose to support that smaller delay now. I3C Basic v1.0 and I3C v1.0 already support a tIDLE minimum value of 200 µs.
Note: The new tIDLE minimum value of 200 µs is safe, as SCL at High in HDR Mode cannot exceed 100 µs (i.e., assuming a typical duty cycle) since the minimum I3C Bus frequency being 10 KHz.