Yeh with vinyl ester I don't think you'll have much issue with laying up the backing coats shortly after it has cured hard. Technically it will continue to shrink until it is fully cured, and because the tooling resin is a different chemical it will shrink at different rates which theoretically can lead to distortion. However in reality they are both very low shrink resins, and I've never had an issue with laying up within a few hours.  

As a home builder working in a non heated garage ive got a system going that's working well.

I do the plug work in the week and then come Friday I start the mould.

Friday evening I put the first tooling coat on, this is followed by a second coat Saturday morning,

Saturday tea time I couple coat and then Sunday lay down the final resin.

If its warm you can work outside, if its cold I heat the immediate work area with a cheap halogen heater, only needs to be running at 400watts so cheap and everything is curing well.

I'm catalyzing at the top end of the recommend levels and getting it down fast, only mixing 200 to 300 grams per mix.👍

Oh ok I did the coupling coat about 4 today so I should be OK to do the next stage in the morning? 

I normally try to layup between 6-24 hours later. Otherwise I give it a quick rub with 60 grit before continuing 

How long should I wait after putting the tooling coat on before I go ahead with the resin and 450csm stage?

Good work.

if you think about it, when you turn it over and are looking into the actual mould you will have a flat facing you that will aid in taping your bag etc

But more importantly will stiffen the mould by a fair bit due to the angle you put in.

Double win.👍

Thanks I've now put an angle on the flanges so hopefully I shouldnt have any problems 

Should work ok.