I am originally a bodyboarder (not bad at it either

I cant beleive how different surfing is to sponging i mean im a pretty good Dker (dropknee) and thought that surfing would be breeze. Man i was so wrong. My pop-up is pretty quick and i get onto my feet okay but staying up is another thing lol. My wave knowledge is pretty good and paddling a surfboard is fine to me feels pretty natural.
Well thats my story heres my questions.
Im sure with repetition ill get the pop-up right (currently doing it on the foamies) But when should i think about tackling actual waves? I remember learning to dk and i only went for bigger waves when i was competant with my balance and stance. does the same idea apply here.
I started practising duckdiving my board and really cant get it right which annoys the hell out of me because ive taken my bodyboard out into some seriouse winter swells and done fine. When begin your duckdive where should your knee/foot be placed and what action should it do to get you under. Sorry im a little confused. Someone told me i should duckdive a surfboard like i duck a body board i cant seem to draw that comparision but anyway ill keep on attempting it.
Thanks in advance for the help