I'm not seeing any benefits to getting and signing a contract at the moment.
I could understand if Ineos were going through a gating process sequentially, and maybe that was the original intention; but they seem to have skipped several gates and gone straight to a delivery date (albeit in a range). If that says accurate, then it's literally the key deliverable. Any other gates on the critical path have less relevance.
Indeed, the only thing a signed contract does for me, is lock in my deposit. I'd be happy to get and sign it on the day I collect it.