Yes u can do two coats to build it out. Personally I'd wait till it s fully dry then aďd pva b4 second coat, some people would just wet it down wiv water but that's more for external rendering, U want the second coat to be pushed into the scratch lines, which should be straight horizontally and not wavy as the second coat could slip down the curves, therefore gripping both layers together. Then flatten and scratch/rub with a plastic float, to a smooth finish. Some people then use a nail scratcher to create a keyed surface for the plaster but I prefer to re pva it the do 2 coats of plaster ensuring the second coat of plaster is slightly weaker than the 1st coat. If u nail scratch it u may find that the plaster produces loads of tiny holes where the nails scratched the bonding the u have to work extra head to smooth them out...or apply a thicker 2nd coat.
Hope that helped.

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