I believe your thinking on this is correct, glitch99. Obviously I cannot be certain, and I also cannot tell you at what time of day your funds will become liquid and, therefore, available to you for withdrawal.
For example, would you be safe to issue an external ACH order on Friday, the 25th, which would be executed at IFCU early Monday morning? I dunno the answer to that.
Curiously I ran into a similar dilemma at PenFed a couple of weeks ago. I had a Sunday maturity. I was unable to find anyone at PenFed who would tell me when my funds would transfer to my savings, something I had prearranged. This cost me a day, because it turned out the funds actually did transfer on that Sunday. Such is life.