A snorkel is OK to use, since it doesn't imprint any bad habits. The reason TI swimmers don't like kickboards is that it imprints a flat body position. The kickboard is basically good at allowing you to endure a kick you'll never use...
The snorkel on the other hand, does no such thing - you can still swim much in the same way you will later, when you learn to fit a seamless breath into your stroke cycle.
However, breathing is where everything breaks down for most swimmer, so be ready for some hard work once you give up the snorkel.