For every province there is a certain gross income the person ought to be making before he/she is eligible for sponsorship. When i filed for my brother, this was last yr around June, i called CIC in ontario and they said i should show gross 22-25K.
You have to find out about your province.
The process goes like this. You fille an application telling CIC you want to sponsor your mother, send proof of ur residency, all supporting facts like health card, now PR card probably, drivers' license, house lease etc and a letter from your bank indicating your bank balance. My attorney asked me to show a balance of 7K+. And ofcourse, your tax returns where CIC gauges your income and whether you can support the person or not.
Next CIC will decide whether you meet the requirements or not, if you do, they will mail you an approval paper saying you'r ok to go. If not, you try again.
Now, with that paper, your mother has to file for herself, asking for PR based on your sponsorship and rest is just paperwork, medicals et al.
The time consuming factor is your approval.
Hope this helps.