It used to be a presumption in philosophy that one could establish the nature of reality thru reasoning. This is essential to the "ontological argument", as well as counterarguments using the same methodology. The limits to reasoning about our universe were forcefully articulated by Kant in his The Critique of Pure Reason, and since then, the value of rationalism to characterize our world has only declined even more than argued by Kant in philosophic thinking.
Ontological arguments are generally seen as self contradictory, and if not that, at least to rely upon unjustified assumptions. I.E. they cannot show the necessity of a God. And as those who deploy them are generally trying to argue for a specific God claim, which IS contingent -- they are off topic as well.
Your counterargument relies upon a variety of suspect assumptions. The most notable is that you deploy a partial form of the Munchausen Trilemma to try to claim that specific possible solutions to the cause of the universe violate "logic". Note, the Munchausen Trilemma applies to ALL possible explanations of our universe, not just to God explanations, and every one of its three legs violates our conventions on fallacies. Is the Münchhausen trilemma really a trilemma? Seeking an explanation for our world is the essence of the scientific project, and calling all possible outcomes of that project "fallacies" is -- not really a problem for science, but instead for the argument that we should not accept explanations.
Your argument also presumes that time must consist of presentism, combined with the logic version of time which is state sequencing. But presentism is an invalid model of time, as other answers have pointed out. Here is a summary of the critiques of all three of our time models: The passing of time
Additionally, a God COULD in principle exist outside of time. This is the most common theological assumption among monotheists. You presume that a God outside of OUR time, would still be subject to time-prime. A time-like logical state sequencing. And your argument relies upon this to rebut the "God out of time" answer. But time-prime is NOT accepted by eternalist God theology, so your rebuttal relative to a God fails on this point.
Finally, you presume that logic is absolute, that there is a "one true logic". But logicians have established that this is not so -- there are an infinity of logics. https://www.cambridge.org/core/journals/think/article/abs/guide-to-logical-pluralism-for-nonlogicians/EDFDFA1C9EB65DB71848DABD6B12D877 An infinity of possible logics, means one cannot make a logic argument and have confidence it applies to our world. And the failure of classical logic with relation to causation, exemplified by the Munchausen Trilemma, strongly suggests that classical logic does NOT apply to our world!
What you do with your discovery is at your discretion. You seem interested in disproving theism, and there are a lot of theists who resort to ontological arguments to justify their views. And those arguments, while they all mostly suffer from the same assumption issues that your counterargument does, could be challenged by your counterargument. A savvy theist could resort to the "God out of time" ploy, which would allow them to reject your counter. All this, however is in the realm of motivated reasoning. if motivated reasoning is all you are really interested in, then this may be all you want to know. Your argument is a useful counter to many versions of ontological arguments. It can be blocked by God out of time, so you would need to come up with some other argument against that debate ploy.
If instead you are interested in philosophic investigation, and the philosophic method, your argument offers a very different value. The basic philosophic mindset is to try to identify, and challenge, the walls of the boxes we think within. Sometimes after challenging them, one will want to live with those walls, but sometimes not. This critique of your argument has identified major mental walls you are using, which are rationalism, invalidly selectively applying the Trilemma to reject science, assuming one known invalid model of time, and assuming One True Logic. Learning to question walls, and to live with porous "walls" to your thinking, and understanding how to do that, is the philosophic project. And your question is a potentially highly useful starting point in that project.
