As per my knowledge  RTM ie prepared before the completion 
of testing because RTM help  you to keep track of the test 
cases coverage at each level of testing.

RTM is prepared by developers before writing the Test plan 
by team lead. whereas TRTM(Test Requirements Traceability 
Matrix) is prepared by testers.

if iam wrong pl. correct me

RTM  maintain the relationship between client requirements 
and test cases.Test cases are written before testing the 
application. so we prepare RTM before testing.

we are preparing RTM before the test execution is started 
(or)after all the test cases are prepared.it is prepared by 
test lead.

hi,we will prepare traceability matrix before testing.with 
the help of TM we will prepare the test cases.

We prepare RTM after writing testcases to find whether we
missed an functionality.So it is prepared before executing
the testcases.

How we write trcebillity matrix .Write the format please

Requirement Traceability Matrix (RTM) is prepared before
starts testing an application. As RTM is used to trace the
requirements with test cases. So after gathering
requirements RTM should pepare. The main purpose of RTM is,
no requirement should missed.

we should prepare RTM before starting testing life cycle
with all the test cases and with required columns like test
case status like New,Open,closed and defer

So before releasing a project we can say easily by looking
at this RTM whether all the test cases covered or not,and we
can able to see the test cases status easily.
so we need to prepare before testing process starts