What is the charge for aggravated assault, if it goes to the grand jury?

Once the grand jury gets through and IF they find sufficient evidence to send to trial you need an attorney. You may do time it is up to a lot of factors but start out with a lawyer on your side.

Here is the definition of Aggravated Assault in Tennessee.
You might use that as a starting point. to see if your situation satisfies all the requirements.

If you are found guilty you will have to do the full sentence. If there was a deal offered, you should take it.

If you are charged, you need an attorney or a public defender. An attorney who has the time to work on your case if you have the money. A public defender will often bargain a plea deal, so you have to be aware of whether this is a good case against you.

And if you can afford an attorney, I’d start shopping now. You need someone known in your jurisdiction and has a reputation for defending people well.

Good luck.

Your question and presentation are so confused that it is patently clear that you need an attorney right now.

“Aggravated assault” is a charge. That is, if you are suspected of having committed an aggravated assault on a person, then that is the charge that will be made against you.

I do not understand why “it is going to the grand jury”, since the district attorney takes prospective cases before a grand jury to determine whether, upon his presentation of witnesses and certain facts in the case, they will return an indictment or not. Since the old saying goes that “a competent prosecutor can get a grand jury to indict a ham sandwich”, there probably isn’t much doubt that the indictment will be returned, you will face charges, and a prosecution will ensue.

I suspect that with the prior conviction, even on the property-only crime (depending on whether you were a minor at the time, and other aspects of the case that may mitigate the sentence), you will very likely be looking at jail time if convicted – which will be a near-certainty without competent counsel on your side, or without a plea bargain that the prosecutor seems to have no reason to offer at this time.

Assuming that it will take “a couple of months to get to the grand jury”, then it may be that long before you are formally charged. I would be talking to an attorney now if I were you.

In addition to what @CWOTUS said, you should also be making plans to get your child temporary or permanent custody with someone who is trustworthy and capable.