Time is of the essence in a criminal case.  If you have been arrested and released on bond, there is a period of time between your release and the time that you are required to go to court for arraignment.  Arraignment is a court appearance where you are asked to enter your plea (of "not guilty," "guilty," or "nolo contendere") to the charges filed against you.  If you plead "not guilty" at arraignment, you are given another date to come back to court.  If you want to have any chance at all to avoid being convicted as charged, you should have an attorney representing you at arraignment.  Certain motions that are critical to the outcome of your case have to be filed within 10 days of arraignment or else they are forever waived unless special permission from the judge is granted.  Do not count on getting special permission from the judge.  Hire an attorney before your arraignment date.

Another reason to hire an attorney early on in the process of a criminal case is the need for thorough investigation.  Witnesses who are critical to your defense must be interviewed; documents that help your side of the case must be obtained; and pictures of the alleged crime scene or other important venues must be taken before important information disappears.