Okay, so I am likely an odd man out here at MDC, but I have taken CO with all of my babies. I would not be comfortable taking it early on, but obviously I am different than most here simply being comfortable taking it at ALL. I do NOT "recommend" it for anyone else, I think that's definitely a decision you have to weigh heavily and make yourself. But I can share my experiences.
With DD1, we tried it because my OB wanted a medical induction, and I did it under the guidance of a VERY experienced MW (previously L&D RN for 35 years) who's advice I really trusted. I had a pretty high Bishop score otherwise we wouldn't have bothered. I tried several rounds of it, but it only sent me to the toilet throughout the day. Nothing horrible, just like I an upset stomach.
With DD2, I took it at my EDD (again, VERY high Bishop score...I tend to dilate a LOT beforehand- like a full 5cm, efface well, baby is always engaged, optimally positioned, and in a very favorable station, etc). I took it before bed once, it didn't do ANYTHING, not even send me to the toilet. Tried again a few days later before bed, and at 3 a.m. I was up, in labor, never had to use the bathroom, and she was out in 4 hours. A VERY wonderful unassisted homebirth, no complications whatsoever before, during or after, labor went amazingly and I pushed her out very quickly.
With DS, again, my body was well prepared for labor (dilation, effacement, position, station, etc). Right around my EDD again I tried the CO. This time it was out of sheer desperation- I'd had a VERY painful pregnancy with SPD pain, SI joint trouble, etc, that no one I saw could really remedy, and I'd been having weeks of REALLY intense prodromal labor (waking up in the middle of the night with transition-like contractions for hours at a time). Again the CO worked, I went into labor around 3 a.m. again, I DID spend some time on the toilet but it was a very short, "mild" experience, and by 3 hours I was complete (though he wasn't born for another 6 hours, I believe he shifted a bit and may have been asynclictic at that point as my pelvis adjusted to the size of his 15.5" head!!!!). Once my body had put on the "final touches" and I broke my own water, he was out in 2 quick pushes. Again, a wonderful unassisted homebirth.