This is what I found.
Using a higher dosage than necessary may increase the risk of having twins. (Ironically, though, using a higher dosage of clomid than necessary may also decrease the chances of pregnancy occurring at all, because higher doses of clomid can create thick cervical mucus.)
Also, women taking clomid who do not have trouble ovulating or getting pregnant, as well as women younger than 25, may have an increased risk of getting pregnant with twins while taking clomid.
Most women will ovulate 7 to 10 days after they take their last Clomid pill.
Remember that some doctors recommend taking Clomid on Days 3, 4, 5, 6, and 7 of the cycle, while others recommend taking Clomid on Days 5, 6, 7, 8, and 9.
If you are on the Day 3 to 7 protocol, this would mean you're most likely to ovulate (on average) sometime between Day 14 and Day 17 of your cycle.
To conceive, you want to have sex before you ovulate.
So, you might want to have sex every day or every other day starting on Day 11 and ending on Day 18.
If you are on the Day 5 to 9 protocol, you're most likely to ovulate (on average) between Day 16 and 19.
In this case, you'd want to start having sex every day or every other day starting on Day 13 through Day 21.
But these are just averages.
It's possible you'll ovulate earlier or later than the average.