Hi Don,
Fresh stucco should be allowed to "cure" before any coating is applied. Allow four or five weeks of cure time. This will allow moisture content to escape. Alkalinity may also form on the surface of the stucco, alkalinity can cook the primer or paint binders. Hose the surface down (with water) once a week during the cure time.
I would recommend that you prime with a masonry block filler or a primer/sealer that is specific to fresh stucco or masonry surfaces, these primers are alkali resistant. Top coat with an Acrylic finish paint or an Elastomeric paint.
Hope this Helps
rmichael propainter