Yeah I called to ask about a week ago, they apologized and said should be done in 2 more weeks.

I submitted online on 30th May and nominated a POSB account so I thought would be as quick as yours... Wonder if it's delayed coz my PR just expired about 2 years ago.

The PR renewal and length of renewal depends on regular cpf contributions from what I've heard and not the amount of tax paid. If you have been working in sg which means regular cpf contributions then when they renew it you will get 5 years.

If you are no longer employed/living in SG and your cpf contribution has stopped for a while, the first time you renew they will likely give you 1 year. The next time you renew or if they don't allow you, you can go online to appeal and list down a reason. So long as you have a compelling reason they will decide on a case by case basis. I.e. Your friend can write that he is studying overseas and plans to return, he still has attachment to SG such as family, friends, belongings there and feels that he is part of the country as seen by his contribution to society and the letter of appreciation he received. Maybe even suggest he will still keep topping up his cpf.

From ICA:
You must renew your REP online using e-Service within three months prior to its expiry date. You are not required to submit any documents, unless requested by ICA.

It's up to you, ideally you do it earlier so that if it's rejected you have time to appeal. If you have a stronger case for renewal closer to the date then wait till 1 month before.
If you have no issue renewing then doesn't really matter.