Was the French citizenship conferred at the actual birth of each, or granted later?
It was granted to each of those Presidents while they were adults - because unlike the citizenship of a child who was born in some foreign country (e.g., Canada), who then left that country permanently at age 4 and had no further relationship with that country at all (TED CRUZ), the citizenship status of THOSE Presidents came about because they had a REAL and MEANINGFUL RELATIONSHIP with the country of France.
In other words, Ted Cruz took absolutely no action to acquire his Canadian citizenship, and he has done absolutely nothing to maintain it.
Presidents Washington, Jefferson and Madison acquired their French citizenship because of their actual relationship, as adults, with the French nation.
The stronger claim of dual allegiance is on those who have an actual relationship with a foreign nation.
Since that was not in any way an impediment to Washington, Jefferson and Madison, not one of whom renounced their French citizenship, and every one of whom held their French citizenship during his term as President, then it can't be relevant for a person like Cruz, who HAS no such actual relationship.