Adding post-master's ACNP

How many of you became an ACNP as a second certification, and if so did you have recent ICU experience for your program?

I had a lot of conflict over choosing FNP or ACNP to potentially work in specialty outpatient, and am enrolled in an FNP program now. I figured if I really need to I can add ACNP after. However, right now I work in ICU and thus have the relevant experience. Say I want to add ACNP in 5 years - would I be in trouble?

It occurred to me a bit belatedly that it might be easier to do ACNP first, then add FNP later as it doesn't have such stringent experience requirements. Now I'm having a wee bit of panic. I still don't want to be locked into a hospital, but as you may have seen in my other threads I've been hearing lots of things about which track is best for outpt specialty. Grr. Not that I want to switch necessarily, but I'm wondering if I might be more locked-in than I thought.