If I didn't want to inject, I'd stick with things like cheese, meat, nuts or a few veggies or similar - anything low carb.
I'd probably test about an hour later just to see how things were going, but that's just me. When I'm out and about, I test frequently anyway as something like shopping can be surprisingly energetic. I tend to snack when I have a break eg a coffee and snack, so I'm sitting down and can sort my insulin easily. I have a pump now, but did the same on injections.