Unfortunately, the iodine has to be available before the third trimester for the full 10-15 point effect. :)

For everyone reading this, it's already far far too late. I've been compiling some of the child & adult iodine studies into a little meta-analysis: http://www.gwern.net/Nootropics#iodine

Current conclusion: for 13+ year olds, the effect size is (95% CI) -0.11 to 0.29. Yes, we can't even rule out that iodine is harmful to adults.