Good morning

I have read many forum threads for STVP extension but couldn't find an answer pertaining to my concern.
I am an Indian holding Studing Pass.
My mom has visted me and she is currently staying here on a STVP.
She has a multiple-entry visa expiring November 2011.
She came on 26th May, 2011 and the stay is valid till 24th June, 2011 (30days) and intending to stay for 2months.
My questions are:
1. When is the best time to apply for the extension?
2. For a higher chance of approval, is it better to do it online or in person at ICA?
Btw: One of my friends, applied for an STVP extension within 15days after he arrived and was refused extension. So I am a bit concerned about timeframe within which I should apply.
I also understand that I can travel to JB or KL for a short trip, but owing to my mom's helath reason, I am tring to aviod that.
I thank you for your advise in advance. Cheers
