Newbie here

Check with the race director.  

Many races have a table where participants like you can place their glasses for retrieval at the swim exit.  Alternatively, they may allow your favorite spectator to hand you your glasses after you get out of the water.  If you do this option, pick a place where you can walk to without your glasses and not impede other participants.  As an example, if you exit the water and have to turn right 50' from the water, have your favorite spectator standing on the left just past the turn.  (It will work far better for you to be on the outside of the turn.)  

While it will seem like some fumbling around, you may consider navigating all the way to your bike without glasses.  Practice the walk from swim to exactly where your bike is racked a time or two with your glasses and again a few times without your glasses.  50-steps, go right, 37 steps, pass under the flags, 24 steps, turn right, 10 steps, your bike!  

Regardless, expect that your glasses may be smudged or spotted and have a way to clean them before you start riding.  

Welcome to the sport!