As users of those PSR, you can start supporting the original & the first of those two releases right away & 2nd+3rd afterwards; example:

psr/link:^1.0 (now, 1.1 already compatible!)
psr/link:^1.1|^2.0 (then)

psr/cache: ^1.0 (now)
psr/cache: ^1.0|^2.0
psr/cache: ^2.0|^3.0

— PHP-FIG (@phpfig) February 4, 2021