It is always a good idea to include QA from the first phase of SDLC. In requirement understanding phase QA gets involved in document review of requirements (SRS). This will really help in understanding the requirement right from the early stages. In Design phase, the main task is to prepare the Test Plan, Test Plan along with test scenarios. During development phase QA will start writing the test cases. , Test data, test scripts, test environment setup etc… Various testing types is performed during the test execution phase and defects are logged. We closely work with the development team in addressing the bug. During the maintenance phase test summary report is sent to all the stakeholders and we also participate in the lessons learnt sessions of the release.