No, there's an event that triggers the end. It seems to revolve around Legion being added to your crew. Once you install the IFF and it's ready for a test - you should be ready to make a decision about moving forward or waiting until after the end sequence of the main game to go back and do loyalty missions, etc.
After you are told about the Reaper IFF mission, you can do as many loyalty quests as you want. After getting the Reaper IFF, you can do only one mission unless I am mistaken. K1LLERAnish 07:23, November 12, 2011 (UTC)
Yeah, and if you did all the missions, the only one left will be Legion's loyalty mission.
An event is triggered that will open up the Omega 4 relay final mission. Exactly how it's triggered is still uncertain but it revolves around how many crew members you've picked up (you need at least 9 I believe before it will trigger) and whether or not you've recruited Legion. You need to immediately run over to him and activate him, in order to be allowed 2 missions before the event (just enough time to open up his loyalty mission and complete it). If you've done all other squad loyalties, Legion's will be available right away. Once you've done the mission, the event will trigger. Once it's done, you're free to put off the final mission as long as you like, but if you don't do it immediately you won't be able to keep everyone alive at the end.
Ok, to actually answer the question, after you receive the Reaper IFF mission in your missions log, that is immediately after the Collector Cruiser, you can postpone it indefinitely and do as many missions you want before it. The only forced missions are Horizon and the Collector ship. The Suicide mission will trigger after you complete two missions after the Reaper IFF; if the only mission available (disregarding N7 missions) is Legions loyalty, it triggers after 1 mission. The Suicide Mission is not a forced mission, but if you do not do it immediately after it becomes available, part of your crew or your whole crew dies. TiberiusYakushev 09:47, November 12, 2011 (UTC)