Am a corporate slave that works by day and graft whenever I’m not working. So night time it is for me!
The main advantages for night grafting aside from it is my available time during the weekdays, is that the scionwood don’t go into a grafting shock compared to daytime. You took the scionwood out of the cool fridge, graft them at night when it is cool and continue to cool down in the morning and then it gently warms up the next day. So they’re acclimatized the night when they’re grafted. If you graft them around noon time, the sudden rise in temperature from the fridge to the sun, and the fact that they’re inside parafilm tape, could be an evnvironmental temperature shock, but then its effect are practically negligble for dormant wood types.
It does matter when grafting citruses or avocados. Early evening is my most preferred time. As the scionwood are taken from their cold storage in the fridge, and are gently exposed to the elements during the night. The stock plants would be well hydrated during the night, and the sap from cut are kept moist.