There were two different LM flight profiles for Apollo missions. <br /><br />For Apollo 11 and 12, the sequence of events was:<br /><br />Lunar Orbit Insertion (CSM engine): orbit about 60 x 170 NM<br />Circularization (CSM engine): 2 (maybe 3?) orbits later, orbit about 60 NM (circular)<br />Separation: about 10 orbits later<br />LM Descent Orbit Insertion (LM Descent engine): about 1 orbit later, orbit about 7 x 60 NM<br />LM Powered Descent and Landing: 1/2 orbit later<br /><br />For later missions (14-17), a different plan was adopted, that enabled landing more mass on the Moon (rover, etc.):<br /><br />Lunar Orbit Insertion (CSM engine): orbit about 60 x 170 NM<br />Descent Orbit Insertion (CSM engine): about 2 orbits later, orbit about 8 x 60 NM<br />Separation: about 10 orbits later<br />CSM circularization: next orbit<br />LM Powered Descent and Landing: 1/2 orbit later<br /><br />The main difference is in these profiles is that for Apollo 11 and 12 (and 10), the DOI is provided after separation, by the LM Descent engine, while for Apollo 14-17, the DOI is provided before separation, by the CSM main engine. However it is done, the LM needs to be at the correct altitude (7 KM) and position to hit it's target.<br /><br />There were some variations from this basic outline on each mission. If you need more details, I would look at these documents:<br /><br />
http://history.nasa.gov/SP-4029/SP-4029.htm<br /><br />and<br /><br />
http://www.history.nasa.gov/<br /><br />Regards