This is the usual nudge and - of course - it comes just as rain arrives in the UK.
However, be warned - we will need a LOT of rain to get moisture levels in the soil even a few inches down back to normal.
Just in case that does not happen, and looking at the forecast it probably won't, remember that newly planted trees and shrubs find it harder to access moisture in the soil than when they are established and so they will need a helping hand.
Final nag - when you water - do it properly. A lot of water at long intervals is very much better than little and often.