May need chg F-2 to H1 later
My company hired lawyer as well as two other lawyers I spoke to myself said that if F-2 is approved, a change of status to H-1B will have to be filed again in September through premium processing in order to work in Oct.
Fan &Fitgerate's mentioned your solution of specifying dates also, but they warned that it may be ignored by CIS. Better to be prepared.