So by doing it this way, i should have 2 copies of each PC card, i don't think there would ever be a need for a third card. If it comes up in the round then you just don't use the other one. For SUPER fast monsters where they are just crazy fast and it's their shtick, i'd just place their card first every round, no randomness involved, they just go First.
It completely depends on if you want to allow Dex or anything else to effect initi order.
With just one card each, it means Dex 8 and Dex 20 have the same chance of going first.
You can use as much, or little, granularity as you want. Instead of just one level, you could have 2, or 3, or whatever you want.
I am thinking about doing this, but will use more 'levels'
Each creature (PC or bad guy 'group') will get one card.
Each creature will get an additional card for each +1 of their Dex bonus
ALert will allow an additional +X cards (Have not decided.... thinking 2-3, will have to playtest)
Please note that PC cards are constant for each fight. So the only 'work' would be to swap out the Bad Guy cards. I could even prep them ahead of time if feeling industrious.
Flip over cards, if your card comes up, you may choose to take your turn or wait for your next card.
It means more cards, but allows the higher Dex folks an advantage for having a higher dex. There is no penalty, however, for a Dex <10. Not common enough to worry about.