It depends which zombs you consider DAHs. If we stick with the descriptions within the show, then Behemoths (first encountered in late June), Little Ones (first encountered and acknowledged at the military reserve base in late July, but already heard but not recognized at the Arena around late June and early July), and maybe Jumpers because of their very different looking (early July) would be the measure; according to that the DAHs showed up the first time a month after the outbreak.
According to CJ the crazy and weird zombies showed up around ground zero, although she did not mention when exactly; but considering that she and her team did reconnaissance before her Tower fell (early to mid June), then those DAH might have appeared as early as during the second half of May - or even earlier.
Based on what we know and what we can assume things remain kind of vague; but I also think it is quite safe to assume that the DAHs evolved early in the zombocalypse, but they did not come from Hawaii ...
Best wishes!
Liam
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