I’m not a banker and only have experience with Bill Pay from 1 or 2 bank accounts. IME, I can input a Bill Pay ACH payment on my (non WF) bank’s website or app until about 7 or 8pm EST, have the payment processed overnight and appear as “received” by Chase in the morning and “posted” (balance decreases and available credit increases) that afternoon. AmEx seems to take several more hours for “receipt” and a little longer for posting.

I’ve only had Chase “pull” a payment (from non Chase bank) once or twice, when I forgot and it was the payment due date. Figured if I initiated the payment on Chase’s website they would see it as occurring on the due date. Took 1-2 days longer for the payment to fully process and my bank account balance to decrease.