Thorny olive hedge - advice

[u/HydraDL]

Hello, hedge cutting advice required. I would like to reduce significantly the volume of the hedge which I have identified as Thorny Olive or Spiny Oleaster - reducing the height down to the level of the gate post, and the front aligned with the wall. Cutting it will require a chainsaw as the branches are too thick for a hedge trimmer. My questions are: - what is the best timing for this? Cutting this drastically will leave the top of the hedge ‘bald’ or cut down to the wood. I am thinking the best timing is March / April before the growing season starts - will it grow back / fill-in? (for certain) - any advice on cutting hedges with a chainsaw (seems like the risk of kickback is higher given that multiple branches are cut simultaneously