If you plan on growing out without the BC, I would suggest that you NOT cut your hair short into a bob. Holding on to the length while you grow out will help you with styling. For example, when time is limited or you are just frustrated, having that length will allow you to slick your hair back into a bun, pony tail, or pin your hair up in some way.
I also transition (unexpectedly) using heat during the most of my transition which lasted 16 months. The last 3 months was probably when I started wearing styles that did not require heat. I've been into hair care for years, so I was cautious when using heat, always deep conditioning, using protectants, etc. My hair looked great and healthy when it was straightened, however, when it was time to wear my "natural" hair I was victim to heat damage. The parts of my hair that were natural softer and looser and texture became permanently straight. It made stlying my natural hair more difficult and very challenging when I first removed the relaxed ends. My last relaxer was December 2002, my transitioned ended in early 2004, when I went for my first cut at Curve Salon in November of 2005, my hair was still so straight in those areas (heat damage along the whole length of the hair) that they still thought I had some relaxed ends! So it took some time to gradually grow out and remove the ends. IMO, heat styling is one of the worst and unhealthiest ways to transition to natural, but experiences will vary.
As your hair starts to grow out, I suggest limiting the amount of heat styling you do. This will also give you a chance to "learn" your natural hair and allow you to get used to your natural hair. You are so used to handling straight hair, you will have to gradually transtion over to handling your natural texture. Experiment with the various transitioning styles that are available.
Good luck!