Clear everything now, like the finances, on your side.
On Friday he should say whether you can still buy, exactly then and not earlier give him the signed application. I would also limit your purchase commitment (e.g. because you are continuing to search in parallel and might commit elsewhere at short notice). Stay master of the negotiation and keep leverage. If it falls through, HE wants to sell to you.
If you sign now, then the next story comes and you keep waiting.
That would be my approach anyway.