OK, y not. I must have somehow missed the bigger point.
It is a good thing that you mentioned that last verse. I did not pay attention to that either!:
‘Na tāvāyaṃ, sāriputta, dhammapariyāyo paṭibhāsi bhikkhūnaṃ bhikkhunīnaṃ upāsakānaṃ upāsikānaṃ. Taṃ kissa hetu? Māyimaṃ dhammapariyāyaṃ sutvā pamādaṃ āhariṃsūti. Api ca mayā, sāriputta, dhammapariyāyo pañhādhippāyena bhāsito”ti.’
It should be actually translated as:
Sāriputta, I did not give this explanation of the teaching to the monks, nuns, laymen, and laywomen until now. Why is that? For I didn’t want those who have progressed to lower phala stages to slow down their efforts. However, I have explained it now, in order to answer your question.”
So, this seems to be the first instance where the Buddha explained how long it would take to attain Arahanthood from the lower phala stages. Basically, one may think that as long as one is free from the apayas, there is no urgency to proceed further. In fact, as I have pointed out before, some bhikkhus needed to be admonished by the Buddha not to “slow down”.