If you really want to level frost invest in Glyph of Frostfire Bolt.
I was just looking through frost mage talents by level and was actually pretty surprised that Brain Freeze isn't a passive until level 77. This being said, I could see how this glyph could possibly help for leveling; however, I would stick to using FFB as an opener rather than your main nuke. I'm not sure this is what you were implying, but FB still has a .25 second shorter cast time than FFB when glyphed and applies a stacking (up to three times...) debuff on your target increasing damage from FB, IL, and your minions WB by 5% per stack making it much more valuable in my opinion. This being said, if you are opening with FFB, you probably need not glyph it because you aren't hurting on time and there are probably better alternatives. I would recommend getting more familiar with shatter combos, as this is the current frost play style as you continue to level. Again though, to each his/her own... if it helps you, by all means glyph it! The devs have been working hard trying to ensure multiple viable options like this are available based on your choice of play style.
Once you reach 77, it is important to note that you will rarely (if ever) hard cast FFB. The only time I use FFB is to consume brain freeze procs at this point. It is an overall DPS loss to hard cast FFB over FB at max level, however I do not know how it scales at your level because I leveled this toon in Cataclysm. Recount or Skada should help you determine what seems to work best!
Now if you have an open mind i might suggest Arcane. I switched it up around 36 and i'm finding things are dying quicker and I feel like i'm getting more Arcane Missle procs than i was getting fingers of frost.
A lot of people agree completely. I'm pretty sure AM has a higher proc rate than FoF, but I honestly cannot confirm this at the moment. The issue (for lack of a better word...) with arcane is lack of utility in cases where you might have to go on the defense. I never had much issue with ether spec (or any of the three for that matter), but frost seemed to be much more "forgiving", if you will, when it comes to unintended multi-mob pulls which are bound to happen when questing.