Sounds like you already have the information you need, but I just wanted to add a few more tidbits about plantar fasciitus. I found it worst in the morning...in my early 40s and I was walking to the bathroom like an old granny in the morning! Now I'm fine! These things helped me the most:
1) STRETCHING IN THE MORNING, before getting out of bed. Lie on belly, toes on bed, and stretch your heels. Slowly, gently.
2) FOOT INSERTS--I bought my first ones from the orthopedist (~$50) but you can buy them at good shoe stores, at EMS, and other places for cheaper (~$30). One brand is SuperFeet, but I'm sure there are others.
It turns out these foot inserts over the years have helped so that I hardly ever have to go to the chiropractor for back issues any more! Double benefits! I have multiple inserts so most of my shoes and boots have them now.
3) CONTINUE STRETCHING, throughout the day. When walking up stairs, stretch your heels by dropping your heel down. Or lean against a wall with your heels down to, again, stretch your heel. (http://www.plantarfasciitisbraces.com/plantar_fasciitis_s...)
4) WHEN SLEEPING, lay on your side and hook your foot over the edge of the bed. This helps prevent the pointing of your toes, because of the covers, and helps stretch the plantar fascii overnight to make it better in the morning. Some people wear foot braces at night but I felt that was too much of a hassle. Others roll up a towel and put it at the foot of your bed to raise up the covers, but I liked hooking my foot over the edge. It has helped immensely.
I was also prescribed some anti-inflammatory meds but the above things made more long-term improvements for me.
Also, losing weight when your special bundles are born might help if that is an issue. It puts less stress on your feet. But words from the wise...it's much easier losing weight WHEN YOU ARE NURSING so try to do it then. I nursed for a year and thought, wow!, why is it so easy to lose weight? I got a little complacent then, and when we stopped nursing, wham! the weight was much harder to come off. Just keep that in mind.
Also, I had been walking regularly on a treadmill prior to this problem. I now walk outside regularly instead. Not sure it's connected, but I think the treadmill led to straining and inflaming the plantar fascii because sometimes I would walk faster than maybe my feet were ready to walk. Now, walking outside, I kind of self-regulate myself. If I'm feeling a little stiffer, I walk slower. If I'm feeling really fluid, I zip along. I listen to my body more than going by a number on the machine.
Anyway, best of luck! And enjoy your little gifts that will soon be arriving!