I dont think Phonemic Awareness, is that important to teach explicitly, as doing Hooked On Phonics and playing other silly little sound games will cover the skill. PA isn't a SUBJECT, but merely a skill.
You can read this wikipedia
article for more a much simpler explanation of what PA is and how it is taught. Knowing that the SOUNDS /k/+/a/+/t/ = cat is a very basic, but very good example of what PA is. Its simply the ability to determine the tiniest sounds in a word or pharse. What sound do you hear at the beginning of the words "pig, paste, pepper, and pony"?
Are these words the same? "pome" "pone" what about "dune and bune?"
PA requires your kid to be able to hear that m and n sound in the first example and realize that the initiale sound of "dune" isn't the same as in "bune"
The fact that your kids are learning so early, this seems like it would almost definitely be a no-brainer for them.
Its hard to believe that anyone would actually be taught PA, I'm guessing its just there to catch those unfortunate children who aren't really spoken to at home and to pad the curriculum of public schools because learning to read seems like you'd naturally realize this.
Using HOP is another bonus. As a good phonics program will naturally have PA built into it. As you see from the examples above, its not something you need to buy a seperate kit for. You could just play a sound/say it slow iword game with your kids whenever you want.
Have them determine which sound is NOT in the word you just said.
IE if they know all their letters and sounds, use CVC like cat, dog, hot, etc, words. but four letters in front of them (for example, D O G T and say "Dooooog!" and ask them to show you the letters that they hear in the word DOOOG or witch letter they do NOT hear (in this case, T).
The short answer, is I wouldn't sweat PA too much, It will develop naturally if you just talk to your kids, but I think it matters even less wth you actively educating your kids from such a young age.