How long can you be held in jail without a bond hearing?

There doesn't always have to be a hearing;  sometimes, bail is set without a hearing, at the time that a judge issues the arrest warrant.  If that happens, you would then need to request a hearing to lower the bail.

Typically, bail will be set within one or two court days after an arrest.  The U.S. Constitution guarantees the right to reasonable bail, in all but capital cases;  however, what is or isn't consitutionally reasonable depends on a number of things, including the defendant's resources and the likelihood that the defendant will run.