The cure time for the LVR 403/LVR 404 (or really any acrylic based product) applies more for detergent washes. You don’t want to have any type of detergents come into contact with the acrylics before they’ve had a chance to set. If an acrylic gets hit with a detergent before its had a chance to fully cure, it’ll basically fall apart and will be worthless. You should be ok if your vehicle is left out over night. For what it’s worth though, you can typically apply a topper within an hour of using the LVR 403 or LVR 404. Personally, I usually apply PolySeal to all the surfaces of my car before I call it a day.