I'm not sure exactly how you're defining this, but
Michał Krasowski's first competition was in December 2013 and his first (and only) WR (3.73 Square-1 single) was in February 2023 (don't know if it's the longest). If you mean time between WRs, it is in fact Jayden McNeill (at ~3093 days). Second place is Cale Schoon (~1736 days, between his 5BLD mean in 2015 and FMC mean in 2020). If you don't count that (since Cale's 5BLD mean was retroactive), it's Patrick Ponce (~1659 days between since 3x3 single in 2017 and his OH average in 2022).
