I always remind myself that every age is a phase - it passes. I've been working from home since my children were 5 months & 5 years old. They are now 8 & 13 - and of course, old enough to reason with
But then, anyone who has ever called me on the phone in the evenings knows that my attention is scattered between four people - my son, my daughter, my grandmother and whoever is on the phone
What worked for me when they were younger was to go by THEIR schedule. There are times of the day that are quieter than others - such as when they watch their show, or take their nap, etc. So I would generally take voice mail, and then return calls when I felt the timing would be good.
There's not a whole lot of quiet time for "getting some serious work done" around my house... so I do try to wake early or stay up after everyone goes to sleep - but that's not always healthy for me (depends on how many hours I need). Fortunately, working from home, we do have flexible schedules, so for me... I just go with the flow, do my best each day (at both family *and* work), go to sleep and then start over the next day...