A method for a cold or warm steam turbine start in a supplementary fired single or multi-gas turbine combined cycle plant including at least one gas turbine, a steam turbine, and at least one a heat recovery steam generator (HRSG) including at least one duct burner in at least one HRSG inlet duct, the method comprising: starting and accelerating the gas turbine to full speed and then synchronizing the gas turbine to a load level that reduces gas turbine emissions to an approved emissions level, directing exhaust from the gas turbine to the HRSG to heat the HRSG so that the HRSG produces a steam flow, when the steam flow from the HRSG exceeds a flow level required to keep the HRSG at a predetermined pressure level, directing the excess steam flow to a waste heat sink and increasing gas turbine airflow at constant gas turbine load to thereby reduce gas turbine exhaust temperature so that steam flow temperature drops to a steam turbine metal temperature level, lighting and loading the duct burner when the steam flow temperature drops to the steam turbine metal temperature level, adjusting the steam flow to a predetermined increased flow level, a predetermined pressure level, and a predetermined reduced temperature level, and then admitting the steam flow to the steam turbine to start-up operation of the steam turbine, when the steam turbine start-up operation is complete, raising steam flow temperature to a predetermined increased temperature level by reducing gas turbine airflow at constant gas turbine load to a predetermined reduced flow level to thereby raise gas turbine exhaust temperature to a predetermined raised temperature level, loading the gas turbine by increasing fuel flow so that the steam flow reaches its rated temperature, when the steam flow reaches its rated temperature, shutting down the duct burners, loading the gas turbine to a final predetermined power production level, and when the gas turbine reaches the final predetermined power production level, re-lighting and loading the duct burner to increase steam flow to a final predetermined power production level and thereby steam turbine power level, whereby the cold or warm steam turbine start will occur when the gas turbine load level and hence related HRSG steam production capacity are limited in satisfying the steam flow and temperature required for the steam turbine start. starting and accelerating the gas turbine to full speed and then synchronizing the gas turbine to a load level that reduces gas turbine emissions to an approved emissions level, directing exhaust from the gas turbine to the HRSG to heat the HRSG so that the HRSG produces a steam flow, when the steam flow from the HRSG exceeds a flow level required to keep the HRSG at a predetermined pressure level, directing the excess steam flow to a waste heat sink and increasing gas turbine airflow at constant gas turbine load to thereby reduce gas turbine exhaust temperature so that steam flow temperature drops to a steam turbine metal temperature level, lighting and loading the duct burner when the steam flow temperature drops to the steam turbine metal temperature level, adjusting the steam flow to a predetermined increased flow level, a predetermined pressure level, and a predetermined reduced temperature level, and then admitting the steam flow to the steam turbine to start-up operation of the steam turbine, when the steam turbine start-up operation is complete, raising steam flow temperature to a predetermined increased temperature level by reducing gas turbine airflow at constant gas turbine load to a predetermined reduced flow level to thereby raise gas turbine exhaust temperature to a predetermined raised temperature level, loading the gas turbine by increasing fuel flow so that the steam flow reaches its rated temperature, when the steam flow reaches its rated temperature, shutting down the duct burners, loading the gas turbine to a final predetermined power production level, and when the gas turbine reaches the final predetermined power production level, re-lighting and loading the duct burner to increase steam flow to a final predetermined power production level and thereby steam turbine power level, whereby the cold or warm steam turbine start will occur when the gas turbine load level and hence related HRSG steam production capacity are limited in satisfying the steam flow and temperature required for the steam turbine start.