At some point you will no doubt experience an addictive desire for soda when you’re at home (will you have some in the house?) AND again when you’re eating out.
I do think it’s best to make one change at a time, and most importantly you don’t want to make your ability not to drink soda be dependent on you eating at home.
I do wonder, though, if you are thinking so much about trying to “get it right” instead of going ahead with the experience of it?
As you’ve already said that you want to completely abstain from soda, perhaps the most important element is getting clear about your intention with that. Do you intend to quit soda entirely? Even though you’ll be making moment-by-moment choices about it, when do you intend to stop? You may want to decide on a period of time to cut down first.