The Bill had passed all stages in both houses of the Oireachtas by 14 February 2024 and was signed into law by the President on 28 February 2024. However, by its own terms (section 1(2)) its provisions were only to come into operation on a date to be specified in an order made by the Minister for Health. No time limit or deadlin was set for making the order, so the Minister could defer the operation of the Bill for as long as she liked.
Commencement provisions like this are pretty standard and, as already pointed out, one of the points is to ensure that there will be time to make the required preparations before the changes to the law come into effect.
So, there would be no excuse for not having a functional website up and runnign on day 1. Even if the IT project ran into problems, was delayed, etc, there was no commitment to a start date; the Minister could defer making the commencement order for as long as was necessary to complete the project.
Having said that, all we have at present is two people reporting that the website wouldn't accept their PPS numbers. That's annoying, but it doesn't necessarily indicate a systemic failure, and we don't see reports in the papers that the system is generally failing. (Do we?) So this could be a teething issue affecting a small number that only emerges when the system goes live, which as we all know from experience isn't that uncommon. From a user's point of view, this is an issue that ought to have been identified and fixed in development/testing. But I know nothing about the realities of developing and rolling out IT services; I just use them. Somebody who understands the business might well say to me that it is unreasonable or unrealistic to expect that all systems will function with 100% reliability from day 1, even though that is what I do expect.