On page 3 of the Schiff memo, we find the phrase
By then, the FBI had already opened sub-inquiries into **** individuals linked to the Trump campaign:
By common usage, one spells out numbers between one and nine, instead of using numerals. A quick measurement of the space used by the blacked out area seems to indicate that only four, five, or nine would fit using the same font. The is corroborated by the blacked out area that seems like it was a list of the individuals under investigation following the ‘:”. The next sentence contains a blacked out area that only has room for two likely words, either “several” or “the other”.
the FBI would have continued its investigation, including against ****** individuals
So, we now know for sure that the FBI was investigating at least four people linked to the Trump campaign in September 2016, significantly before Comey’s letter about Hillary’s emails.