if the birds have been separated for a while, then in good breeding condition, they often" take" right away,, if they dont, its well worth keeping an eye on the cock bird, as he can and will roughen up the hen , often to a very bad degree, an upside down galley pot, or a half brick can save this, as the hen can hop on to this and get some protection, but i find there are certain birds take to other birds that they in fact" fancy" ,, mating birds can be quite difficult , especially with yearlings, i find it better to let each pair out their box [with the other boxes closed , also a pair at a time outside,,,,, by spending time with them, in getting them used to their boxes, they will hopefully settle ,, good luck