Yes, more Black Lives Matter protests could have been avoided with earlier release of information regarding FBI surveillance. The fact that the FBI was monitoring the BLM movement itself would have deterred many of the protesters from joining the movement. This does not mean that the movement was negative or should be categorized as criminal.
BLM protests are meant to be a non-violent way to bring attention to the fact, that even today, black lives are not treated with the same resepect as white lives. Until this stops, and until everyone is treated equally they will continue to protest peacefully in order to spread their cause.
The BLM protest occur mainly because the members have their own agenda and seek opportunities they can exploit. Modern technology puts smart phones with video recording capabilities in the hands of practically everyone. When some possible police abuse occurs, the video evidence of it is released before any investigation takes place and the protest are already being organized.
Black Lives Matter protests could not have been avoided by earlier release of information because BLM protests are not only about information not being made public quickly. The main issue behind the BLM protests is some police officers' tendency to use excessive, at times deadly, force- often prejudicially against black men. There's no timeline of information that could prevent that after the fact.