Olympic rehearsal start dates range from mid-April to mid-June depending on the segment - and they are specific to number/initial groupings until much later in the process when groups appear to start coming together. There's nothing to stop another grouping of 'late entrants' being put together with a later start date and perhaps slightly more frequent rehearsals until they catch up.
Paras - we have no idea. No-one on here has an offer - and it's only when you get an offer that we have any clue about the rehearsal schedule. If you work on the principle that it's 5 weeks later, then that would mean that they won't start until towards the end of May but that's total speculation.