While writing my dissertation for my PhD, I was told by my IRB that my target population (study participants) had to be very specific which required an update in order to be approved for actual interaction with this group. If they have honed the requirements for study participants, then that might mean they are getting close to being approved for the study. IRBs (or ERBs) are necessary to make sure all facets of a study are "up to snuff" whether it be methodology, type of study, protection of participants etc. but you can't get before them until you are ready to put your plan into action. At that time, they review your proposal and suggest changes that will keep your study valid (maybe, your participant population is too broad)so that a positive peer review will be more likely. Data collection can not start until then.