I guess we can only hope that once the Grand Jury indicts him, then he starts talking...
And I'm right in thinking the GJ will be end of Feb beginning of March?
GENERAL CONCEPTS
1 We have no idea when the GJ convenes. LE has one very broad limit.
2 The broad limit is, LE has to have an indictment by a deadline, or else they must release EA from jail.
3 Deadlines vary, depending on the type of crime, but my understanding is that they have until mid-June in this case.
4 The GJ for this matter is convened and hears testimony at the sole discretion of LE. LE, not a judge, determines the start, time, speed, the length, frequency of presenting testimony, etc.. FWIW, the grand jurors will probably hear a slew of stuff that no one else will ever hear.
5 The GJ could have (and likely has) already started hearing witnesses and evidence. It's private, it can be intermittent, and no one would know besides the people involved (judge, LE, jurors, witnesses).
6 The GJ can be used to compel testimony under oath without cross-examination, so it can be an investigative tool. For example, LE may use it to get sworn testimony that might help find CM, say by making the Arochi's answer questions.
7 However, until there is an indictment, the defense has no right to know what they are investigating or what they have found already. So LE may wish to look for more evidence for a while, use the GJ as an investigative tool, and drag their feet on an indictment, in order to keep their discoveries secret.
8 I have to believe that the GJ testimony, and investigation, is being used to (also) dig out evidence for a murder case, without any interference from defense. LE has super-wide latitude in a GJ proceeding.
THE ANSWER TO YOUR QUESTION
Yes, CM's family has said that there will be an indictment around the end of this month. But, we have no way to know what they have based that on - LE may have said exactly that, hinted at something like that, or said "It can take 2 or 3 months from the arrest" after which the family drew their own timeline. As I noted earlier, the time frame is fully up to LE, and based on the evidence we have already seen, imo they would have no problem getting an indictment as quickly as they wanted to.
If they want to do so quickly, that is.
LE's limits are "now to mid-June" and they can probably pretty much pick the day to ask for an indictment, and get one.