As above
The 'standard' training plans are 30 weeks, so you are not behind that much.
However they start with about an 6-8 hour traniing week..... (I think) with 2-3 * 30 min runs, 2-3 * 1-2 hour bikes and 2-3 30 min swims. However, this is just to get you into the swing of training every day.... before volume training ramps up. If week 1 is killing you........
This will increase to 12 hrs+ up to 20hrs a week for the bonkers/committed.
However, on race day you will be exercising between say 12hr and 17hrs depending on your speed, so I think its a fair idea to do at least that level of training in a whole week instead of 1 day at some point...???
Perhaps those that went from nothing to IM n a year can give better guidance on this one...?