Although a report in Travel Weekly about increased summer flights capacity being offered by Jet2 did not specifically mention Mallorca or the Balearics, there is a separate report from the Palma-based travel magazine Preferente which states that Jet2 have informed hoteliers in Mallorca that they have scheduled the "massive" arrival of British tourists on the islands from June 2.
May 17 is the date that Boris Johnson gave for foreign holiday trips to restart, and Jet2 will have specific flights from then, but the holiday push - it would appear - will really start in the first week of June.