Update:
I applied on 30 July, 2015. Then the timeline was normal. Got AOR three months later, and OWP four months later.
Today I, the main applicant, received an email says:
"This confirms that your application for Permanent Residence under the Spouse or common-law partner in Canada class has been received by Citizenship and Immigration Canada (CIC) on 30/07/2015."
This seems an AOR for the applicant , after another four months since the sponsor got file number. Not sure what does this mean.... maybe means nothing?