How to prime this door frame?

[redhexagonal]

I have several door frames and architraves to paint. I’ve sanded back alot of the old gloss off the frames. There are some knots to treat. Although the MDF is primed I had to sand some bits back so that needs re priming. I have Zinnser BIN, should I spot prime the knots and use some kind of cheaper primer over everything, or just do the lot with BIN? Or something else? I’ll probably put dulux satinwood white on top, or maybe a water based paint with a similar sheen.

 

[hants jobber]

knot, (bin can be used for this), spot prime (mdf), prime, (wood) stop holes, spot prime again, gaulk gaps, two coats of satinwood. all depends on your wallet