The normal way to say 'in the evening, at night, in the morning, in the afternoon' is to use Instrumental case, i.e. вљчером, нћчью, џтром, днём. However, the Genitive is used when the hour precedes:
двђ часђ нћчи (note the use of нћчь for the wee hours) two in the morning
сљмь часћв утрђ seven AM
в сљмь часћв вљчера at seven PM
в двђ часђ днї at 2 PM
вљчером (Inst.), часћв в вћсемь in the evening, around eight