The Hooks Lane outfit included five newcomers in their starting line-up before running in six tries for their bonus-point win.
Head coach Will Knight was pleased with the way Havant disposed of difficult opponents.
‘It is a really good start for us and it was nice to see some of the stuff we have worked on in the summer put into practice,’ he said.
‘As coaches we see our job as providing the players with a toolbox.
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‘When they adapt and make their own decisions on the pitch then we know it is working.
‘I felt we did that against a decent London Cornish side in a far from straightforward win.
‘It is a good start but we have a lot of experience in our team which will ensure we keep our feet on the ground.
‘After the game the players were talking about what can they do differently and improve.’
Joel Knight gave Havant the lead with a second-minute penalty.
It was the hosts who grabbed the first try on 16 minutes before Joel Knight responded with another penalty.
Harrison Young scored Havant’s first try on 24 minutes – bursting over from close range.
Jerome Trail then ran in from 40m to make it 18-10 at the break.
A couple of penalties allowed Cornish to reduce the deficit early in the second half.
But then Havant took charge with Dan Munden, Armandus Morgan, Harry Carr and Will Brock all scoring tries.
‘Our fitness levels were very good and as the game wore on we had the edge in that area,’ added Knight.
‘In reality in the end we had just too much for the opposition.
‘We are pleased to start with a win but won't get carried away by it.
‘It is important we build on it and move on.’