Hi Andy.
Well, as you say it depends on individual use and your tolerance and dependence levels.
The average amount people vape is 2ml per day.
If you smoked 20x0.6mg then you are losing 12mg per day if you stop.
That's 2ml of 6mg eliquid.
But and this is a big but ... that's if you spread your 'allowance' evenly throughout the vaping day. If you vape zero and have occasional spikes when you have a craving for a smoke then you could use 1ml of 12mg per day and as much zero as you want.
I'm finding that zero/low with medium/high spikes is much more satisfying than an even level of low or medium. It's much more like the spikes we get from smoking and tolerance doesn't build up and ruin the effect, you can get a buzz with low this way.
Everyone has their own strategy so it's really a trial and error thing. You aren't used to high levels of nic though so go easy and if you want to take high build tolerance gradually. It's probably better to take some high nic to satisfy cravings than to take low and not be satisfied and be tempted to smoke.
EDIT
We keep posting at the same time Sanner
It's good to be back, I couldn't get this forum for a while after everyone else could. I like Right to Vape too, it feels like it's going somewhere but there's lots of chatting to do here
That sounds about right Jim, 0.3ml for superminis, 0.5ml for minis and 1ml for classic/penstyles.