The most likely option, imo, is a pre-TP split-- this allows both BotW to occur on the Child Timeline and Castle Town to remain in its OoT position/the Temple of Time to remain standing without any inconsistency. But it may also occur simply post-TP, on the CT.
Or place it on the DT, as we don't know the fate of the ToT on that line. Also, we have precedence for multiple ToTs. And geography probably isn't the best indicator of timeline placement when you compare it to the lore references. And most lore references support the DT:
-The events from later parts of OoT are remembered(Ruto fighting Ganondorf alongside the HoT, Nabooru being awakened as a sage) these could theoretically also work on the AT, but Hyrule was destroyed in the AT.
-The Royal Family has the complete Triforce, something that has only happened in the DT as far as we know, and is something that's a recurring theme on the DT.
-Ganon is a primal evil as said by Impa, and is at his most inhuman ever in this game, with Zelda in the JP version of the final battle saying that he has been revived many times and destroyed, something that has only happened in the DT. Also, Aonuma said that this is in the timeline that has many battles with Ganon, and the DT has the most.
-Hylia is worshipped. The only evidence of Hylia worship post-SS is in AoL due to the Goddess Statue, and ALBW where Yuga says that Zelda reminds him of ''Her Grace''. These games are both in the DT.
-The MS is in the forest, with the flowers in the same position as in ALttP and ALBW.
-Hyrule is in a state of decline, something that we only see in the DT, and is a recurring theme.
-Lynels have only appeared in the DT. Although admittedly minor, maybe even weak, evidence, it's something to think about.
-The Tunic of the Wild resembles the tunic that LoZ/AoL Link wore, and is said to have belonged to a previous hero in its description. It's also the only green tunic you get without an amiibo, making it the only canon green tunic.