Unlikely. Most likely an early rotation out of the City and back...No doubt heavily subsidised by the Manx Govt......
Tying up an Embraer for a whole day (which is what 3 rotations on this basis would do) with unattractive timings to boot (can't leave LCY before 0700, and there's not much market for outbound from LCY at 0700 anyway) sounds remarkably expensive. If the 3/daily rumour is true I'd be more inclined to suspect a Dornier 328 from SunAir, another Saab 2000, or something similar in the 50-seats-or-less range.