From an interview with Bay after the first film came out, that was also true of ROTF.

Bay stated, in an interview, he wanted to take a year out to do Pain and Gain, whilst the script for ROTF was being written. Presumably, Bay had planned that he'd be done with Pain and Gain by late 2008 and ROTF would start production in late 2008/early 2009, possibly for a 2010 release.

However, in response to the writer's strike, Paramount made the writers rush the script (it was written in three weeks) and had Bay begin production before the script was even finished. And I don't need to tell you how that turned out. Following that, Paramount and Lorenzo di Bonaventura made loads of other idiotic decisions... which got us in the mess the TF movies were in before Bumblebee.