If you are in custody ( I assume you are not if you are posting this) then they have 90 days to indict you otherwise you must be released on bond, though they can still proceed with charges.
If you are not in custody the only specific time limitation is that they must indict before the statute of limitations runs, which is 5 years for these charges.
There is a general right to a speedy trial which also implies a speedy indictment. This is not a statutory right but a constitutional one under both the Texas and US Constitutions. There is no set time frame on this and it is viewed on a case by case basis but generally there needs to be not just a significant passage of time but a showing of a loss of certain liberties as a result of the charges not being filed (ex: loss of employment, reputation, etc..) There also must be a showing of a lack of due diligence on the part of the State. Finally, a major factor is whether you have filed a motion for speedy trial/indictment and not subsequently waived it (asked for continuance or fled the jurisdiction.)
If you are trying to get the State to hurry up and indict you the best way is to file a motion for an examining trial. Whenever it gets set they either have to indict you before that date or they have to appear and prove up probable cause to the judge, which is alot more work then just getting it indicted.
