Looking at my past visas: The date you applied for a visa (and it was granted that date) is the first date you can enter PRC. So, if you applied on Feb 20th, Your visa would say: Enter before 20May2009, and the issue date is 20Feb2009. Meaning you can enter PRC at anytime inclusive of those dates. If it says 30 days duration each stay, you can enter on 20th May and not have to get out till 19th June. In effect, you can stay in PRC for almost 4 calendar months. For your 3 months visa, provided it says 30 days duration each entry.

As Mr Reggie says, but also, my visas do mot say '3 months' but '90 days'. So that handles short or long months. Also Reggie is implying a multi-entry visa. A single entry visa is valid from the day you enter for the number of days stated, including the start and final days but once you leave you cannot re-enter. If it is multi-entry it is as Reggie says.

Yes, my bad! There's no such thing as a multiple entries 3 months validity visa.

Also, when they issue a visa, the first possible date to enter might be Dec 16 2008, for instance, then if 3 months validity, the last possible date to enter would be March 16 2009. They do not seem to bother to count the days, probably cause they do not offer a xx DAYS visa. It is 3 months, 6 months, or 1 year.

Oh yeah, checking my visas, I see that one of my 6 months visa commenced on, say Oct 31st 2007 with validity ending April 30 2008.

I guess you can complain about being short changed if if you can show that the last day in April falls on the 31st.