The most important thing is your intention! Whether the Sun touches it or not 
that only matters if you believe it matters. You can simply collect your water when you wake up, regardless of the time or if the sun hit it.
The reason it’s worded like that in the Moon Water Recipe is to discourage a beginner from just leaving the water there and then forgetting about it until a week later when they find it… 
Any blessing ritual requires to be mindful throughout, in this case throughout the night.