I generally keep it last in the routine and mark it complete right as I put away my phone. It feels like a commitment to myself, so I usually don't end up keeping my phone out after I mark it complete. That said, you could also consider disconnecting to be something like plugging it in at its overnight charging spot outside your room. I think it's helpful to remember that it's meant to be a ritual, so whatever that looks like for you should be fine 🙂
I start my disconnect nature sound & out my phone away while I read my book. Then mark it complete once I’ve finish my reading for the day. Or I check the box & put my phone to charge away from self , relax & go to sleep.
I usually check it off the morning after. That way I know for sure that I did disconnect that night, rather than checking it off before and then forgetting and not disconnecting.