Eh, honestly susah nak judge timing ni sangat precise sebab setiap orang beza, ada yang egg white keluar setengah hari je, ada yang bertahan longer. But based on what you shared, if egg white tu keluar tengah hari dan hilang petang, ada possibility ovulation boleh jadi dalam 12-24 jam after tu, so BD at 12am malam yang sama ada still decent chance, especially since sperm can survive a few days. Since your OPK was still faint sehari before, timing tu macam dalam the fertile window range lah. One of my mum friends yang trying to conceive dulu dia pun noticed egg white hilang lambat and still dapat pregnant with BD malam tu, so don't lose hope! But honestly, if you want to be 100% sure about your ovulation window, better track with a fertility app or check with a doctor/gynae, they boleh advise better based on your cycle pattern.