DTCI - to call or not to call, that is the question...?

Hi all,
Just looking for some clarification re: booking in for DTCI. We're flying in little less than a month so I called UC to book a slot, but supply the car details on the day (we'll get an Uber and I'll call once I have the details). However the CS rep told me just to call on the day with the details (half an hour before arrival). Just want to check others experiences as I was pretty sure booking a slot was still the done thing for a smooth entrance etc.
I'd like to avoid having to wait and make things as easy as possible so any thoughts would be great (I know it's changed a bit since the last time I used the service!). Thanks!
Just looking for some clarification re: booking in for DTCI. We're flying in little less than a month so I called UC to book a slot, but supply the car details on the day (we'll get an Uber and I'll call once I have the details). However the CS rep told me just to call on the day with the details (half an hour before arrival). Just want to check others experiences as I was pretty sure booking a slot was still the done thing for a smooth entrance etc.
I'd like to avoid having to wait and make things as easy as possible so any thoughts would be great (I know it's changed a bit since the last time I used the service!). Thanks!