I only have experience with SGSAH, but it likely applies to all other AHRC consortia.
DTP funding is only granted for those starting their PhDs in the autumn semester. And normally you'll have two application processes running somewhat in parallel: an application for a PhD offer from your university, and an application for funding from the relevant AHRC consortium. In order to apply for AHRC funding with the consortia, you first need to apply for a place with the university and normally join an internal competition to have the university nominate you for AHRC funding. This normally happens between November and January, and IF the university nominates you, then you'll be able to apply for funding at around late January/early February, for a PhD starting in the next autumn semester. Then funding results typically come out between April/May, which is why there are so many stressed out people in this forum right now (myself included).
So yeah, it's a really drawn out process where we're expected to do everything far in advance and do a LOT of waiting. If you want to apply for the 24/25 cycle, I suggest you start contacting prospective supervisors and working on your application now, as you'll be expected to have a well-rounded proposal by November.
I realise I may not have been very clear, so:
November-December of the previous year: apply for a place in the university and enter the internal competition for an AHRC nomination
January-February: hopefully get an offer and a nomination, apply for AHRC funding with relevant consortia
April-May: hopefully get a funding offer and celebrate like crazy
September-October: start the PhD you applied for a year ago