Dimitry,
>>On what occasion? (Kaa uppatti?)<<
This is referring to the cause of the sutta verses. 'What was the origin [of
this sutta]?' In other words, why did the Buddha utter these verses to
Rahula?
>>And [his] son Rahula, in development of this going forth, was given higher
ordination by Saariputta Thera (Eva.m pabbajita.m pana raahulakumaara.m
vu.d.dhippatta.m saariputtattherova upasampaadesi)<<
Vu.d.dhippatta.m refers to attainment of age for full admission as a bhikkhu
(20 years). In other words: 'Now having went forth in this way, when the
young Raahula had attained the proper age the elder Saariputta also gave him
the full admission.' That would be 13 years after the original going forth.
Sean