this stuff is on my mind, too - though i feel like we have a bundle of time since DD's only 5 and i don't think we can send her back to traditional school at this point for several years (radical acceleration.)
whatever approach you do choose, you'll no doubt be able to keep yourself on the straight and narrow once you have established the curriculum expectations in your area. but you might also find that some of the panicky feeling dissipates once you actually get going - i think that's pretty common for homeschoolers!
i think one of the reasons is that when it's a one-to-one ratio (or one-to-three in your case,) there's just so much time available to try things/make mistakes/see success.
even cooler, i've found that almost everything we do actually supports a few parts of the curriculum simultaneously - albeit sometimes across a few grade levels at once. for example, DD5 wrote a letter to my mother as part of school last week. it started off as a regular thank-you note, but it really turned into handwriting + spelling + letter formatting + date formatting + letter writing + sentence structure + thought organization, etc... nearly everything we do works out that way - and even better, often sparks interesting tangents.
your method and style may change as you go - and you may find that different approaches work for different areas of the curriculum. why not start with some weekend sessions or some after-schooling to get your feet wet - just a little here and there to see how it flows? you could try an outing somewhere like a museum and then build up a lesson structure around that?
but take heart - you've been teaching your little ones from the very start, and this is just one more phase. and... like my mother always said, "beginnings are difficult!"
