Certainly agree with Ginagirl about supporting both thyroid and adrenals. Iodine will benefit both. If you try to force your body to do certain things, such as be off HC before going overseas, you could end up overseas in a crisis with no HC at hand. Don't presume you know how your body will respond to a new environment, and take with you whatever has helped you weather storms in the past.
It seems you may think of iodine as a therapy that you begin and then complete. This leads you to worry whether you should take it now, or take it then, or take it after something else. Don't worry. ALWAYS have iodine in your life. It's best use is not as a therapy, but as a supplement for your body, to be used forever and always. Immunizations will come and go, but iodine will always be there to support all body functions. Start now. Since you're worried, start low. Allow your body to adjust, then increase the iodine. Eventually you may find a working dose from 50 mg-100 mg, but some take more, and some take less.
Yes, when your thyroid and adrenals kick in, your rT3 will dissipate. But if your levels are too high, your thyroid hormones will have trouble reaching the cell receptors, because they'll be clogged with rT3. Temporary use of T3 can help clear rT3 and get you back on track. More on rT3 here:
http://www.stopthethyroidmadness.com/2009/11/18/reverse-t3/
My vote for women is Lugol's or Iodoral. Breasts need more iodine than provided by Nascent or Magnascent, IMO.
For a comparison -- http://curezone.com/faq/q.asp?a=13,281,2962&q=579