Based on the you are company followes project life cycel.

different companies follows different types of software 
development models,depending up on the size.In small and 
medium companies follows a clasic waterfall model lik 
model,in which testing is starts after development process 
is complets,some medium and big organizations follows V 
model lik model in which testing starts right from Business 
requirment documnet or SRS,and it will continue untill 
product relese.

as soon as possible when the requirement is getting

Based on the system requirement specificaiton(SRS) we will 
write the test cases and then starts testing.

It depend on the life cycle model of your company.
generally aafter preperation of the test cases they will be 
get approved from the client.
before starting the execution shake out will be done to 
check weather the build was done properly or not on the 
application
this is call as FFA.

Testing Starts "As early as Possible" in the development
life cycle.

Static testing or Review used to test the SRS, FS, TEST PLAN
etc.... 

Prabhu Subramanian
CSS India Pvt Ltd.

Actually testing starts from the requirement phase onwards.
Once the requirements are baselined(srs) then we will go 
for writing testcases.Execution of our tests will be 
started during the testing phase after the release of the 
build.

Testing should be start end of software development and
After prepare the test plan of the project