In my highly uneducated and rookie opinion the first question in the above comment hits the nail on the head, what do you want out of triathlon. Are you after Front of Pack results with World Championship qualifications or are you happy to compete and provide an example to your children of what you can achieve in life in the hope that they may follow in your footsteps to compete as well, which will lead to greater time spent together.
I have three children (5, 9 & 13) and fully understand my place in the triathlon world. I have no aspirations for World Champ qualifications and am happy to be able to front up and give an honest effort and finish.
I have gone through the frustration in trying to prepare for my first 70.3 with all the grand plans of programmed training sessions only to be unable to do them due to life getting in the way. Be it children not sleeping, working late, wife working late, family event commitments and the list goes on.
The greatest piece of advice I feel I can give you (because it helped me) is to roll with life and accept your place on the triathlon totem pole. If you hold aspirations to become front of pack your children will be out doing their own thing in a few years’ time and that is when you can ‘ramp’ up your training.
Now in regards to fitting things in now around life, try to use the commute to work if you can. I have just started to ride to work, with it being just over 20km each way I am getting over 170km of riding (almost 3 ½hrs) in each week as one day I need to catch the train to be able to pick the girls up from dancing one night during the week.
Short half hour runs in the evening once or twice a week with a long run (1hr at the moment) on a weekend. This can either be while my middle one does a boxing class or Sunday morning before the wifey gets up. This way we still have breakfast together as a family.
Swimming is the issue at the moment but as my 70.3 goal isn’t until December I am just doing what I can and will see where life takes me in the months to come.
Just do what you can but most importantly accept what you can otherwise you will become bitter towards yourself and those around you.