Are either of these good translations of 'from 8.12 to approx. 8.30'?
с двенадцати минут девятого до примерно (or часов?) половины девятого
с восьми двенадцати до примерно половины девятого
Basically, I don't know if, after 'с', all of the time expression should be in genitive.
Also, how would you say 'from 8.48 to approx. 8.30'? I don't think it would be 'с вез двенадцати девять...' etc.