I would first spray the new wood with what is known as a wash coat.
Then, after this dries and a very light sanding, you can apply an oil
stain such as penetrating oil stain or architectural penetrating oil
stain. It will have to sit on the wood for couple of minutes. The
wash coat is basically a thinned sealer coating. This is how poplar
or pine is usually finished.
I do not use poly for a finish, unless it is to touch up an existing
poly finish, because of the drying times. Lacquer such as cabinet
lacquer is non-acrylic and is usually nitrocellulose lacquer. Both
poly and lacquer are bad for your health so use a well ventilated area
and a mask. No stain by the way will stain poplar evenly without
a wash coat.
The new book by Bob Flexner about wood finishing goes into detail
about this problem. It is "Understanding Wood Finishes".
Don Teach - Shreveport Music Co.