as the soil is still warm then yes it is a good time. pop it into a hole that is at least half as big again as the pot twice the size would be better as that extra loose soil/compost will encourage the roots to explore and it will drain easier.

if your soil is alkaline add some ericaceous compost/leaf mould/leaf litter to the soil you've dug out. mix it well and the use it for the back fill. Don't have the stem lower than it is in the pot though.

then keep it well watered until the autumn rains take over.

Thank you Sbg, the area I have planned is west facing which will suit it too..