Hi! Congratulations on your pregnancy! It's quite a journey!
My son was born in August and I ran right up until 35 weeks. I ran the Goofy at 11 weeks and a local half marathon at 35 weeks. I don't recommend the third trimester 1/2 after having done it, but 24 weeks should be very doable if you're having a healthy pregnancy.
Two things you may or may not be prepared for:
1) Your heart rate will be higher because your heart is working to pump blood to your little one. My resting heart rate went up to 95!

This means that you have little room between your resting HR and your anaerobic threshold than normal. You also never want to cross this threshold because it means that less oxygen is going to your baby. Some OB's will give you an arbitrary HR not to go above (150 is pretty common), but if you know your pre-pregnancy HR zones, you can use this - for me, I know that I go anaerobic at 167 so I set an alert on my heart rate monitor to beep when I hit 165. If you don't currently use a HRM, now is the time to buy one and use it.
2) Your body is pumping out a hormone to stretch your ligaments to prepare your pelvis for delivery. This makes it very easy to injure yourself. I dislocated my knee while strolling on flat, level sidewalk.

Stretch, walk if something hurts, and ice any "hot spots". Also consider supportive insoles for your running shoes - your arches will flatten if you don't give them TLC.
Oh, and HYDRATE!!! After about 20 weeks, I would get Braxton Hicks contractions if I wasn't extremely hydrated. I had to carry water on every run, no matter how short. And you're going to want some comfortable running gear - runningskirts.com makes a maternity running skirt that I can't recommend enough. It covers the gap between your too-short running shirt and where a regular skirt/shorts would sit, and helps support your belly.
Those are the big things. Also, talk to your doctor about warning signs. My doctor was comfortable with me running up through my third trimester but we discussed the situation in which I would cut a run short - more than 4 BH contractions in an hour, cramping, or spotting. I always ran with the knowledge that I might need to stop and carried a cell phone so I could call someone if I had trouble. I only had one "nervous" run in the 8 months that I ran pregnant... a 5K at 32 weeks where I pushed myself too hard.
I think running through pregnancy is great, if you are having a healthy pregnancy. I had a textbook pregnancy, an easy delivery (5 hours from start to finish), and a fast recovery. I give some of the credit to keeping active until my 9th month. The worst part I found was finding bathrooms every mile along my route!
Congrats, again, and I hope everything works out for you!