Hi A.,
I have been a WAHM for 3 years now and I have to say it is so much harder than when I worked FT outside my home. I have 3 girls 12, 7 and 16 months so I completely understand trying to entertain while working.
I have found that having a set schedule with "business hours" has really been a blessing. I have also found if you can get outside your home a few hours a week, like to starbucks, and get busy work and phonecalls done that is productive as well.
If you have a business that requires you to go outside the home then pick some combination of days for you to be available to others and stick to it. That way you are more organized with a set schedule and you know what to say when people ask your availability.
My youngest starts MDO this week too so I have set my schedule around that. An ex. is Tues & Thurs while she is in school from 9-12 I am outside my house somewhere that has free WIFI working on my business only. From 12-3 on those days we are back at home and she is napping so I am doing house work. MWF we have atleast 1 playdate with our playgroup and naptime is used to get house work done again but also to prepare for "workdays" and return phone calls. Thurs night & Saturday afternoon are used for work only as needed and is also used for "me" time so I go to dinners, movies etc. with my moms group. No work on Sunday!
If you find yourself getting too busy then I would also say you need to look at having someone help you. You can use a virtual asst online or find a high school student for cheap. Even another mom who maybe would work for product if you have it might be willing to pitch in. :) Also invest in an organizer that is made just for us. I never used one until I found the momagenda and now I don't know how I lived without it!
That was alot but I hoped I helped! It sounds like an exciting time for you. Good luck!