1 part epoxy primer and more primer..

We are quite limited to what we can buy here in Canada so I am looking a Nason. In the TDS is says 2 coats are better than one sprayed at an interval within 30 to 60 minutes based on temps..
Yes but, how long after can it sit without being covered by a fill primer before you have to reapply epoxy? For example the PPG Shopline epoxy can't sit for more than 2 days if it sits any longer it needs to be reapplied.