I’ve always done it until Pentecost too.
Fisheaters is a more traditional site, so perhaps it used to be through Trinity Sunday.
Works with me !!
However, I finally flipped through the 1962 Roman Catholic Daily Missal that we use most commonly at the Mass I attend (at a Diocese Parish, with the TLM done by the Institute of Christ the King, Sovereign Priest). The missal is published by Angelus Press (the copy I have was printed in 2004). For what it's worth, I found a section in it entitled "Eastertide". The very first sentence in this section reads "Eastertide begins at Easter and ends on the Saturday after Pentecost".
Oh great, a THIRD opinion!!!
: )
I suppose I will just show this to Father at some point, and as his opinion.