At your arraignment, two things happen: (1) you are formally charged with an accusation, indictment, or information, and (2) you enter a plea of guilty or not guilty, or if you stand silent the court will enter a plea of not guilty for you.
What many people don't realize is that when you enter your plea, the clock starts ticking. You only have 10 days to file motions after arraignment, or you may lose your right to challenge the legality of searches, interrogations, how the charging document is worded, and other such things.
Once you're arraigned, the court starts you on track toward your trial. If you delay in hiring an attorney, you may lose the right to hire your own counsel. I've had people call me the week before their trial is to start--by then, it's too late. The court may not permit me to represent you. And if the court allows it, we're operating at a disadvantage: either we go to trial on time and I only have a week to prepare your case, or I demand a continuance and the court decides to grant it but also hold it against us for the rest of your case. Think how many different ways a pissed off judge can make our lives more difficult!
If your arraignment has been scheduled and you want to hire a private attorney, you need to act now.
If you want to hire an attorney but you need time to get the money up, the court may grant you one continuance--typically a few weeks--in order to hire a lawyer. But you must show the court that you're serious about hiring a lawyer. Go talk to some lawyers, take their business cards to court, and show them to the judge. Tell the judge what you're doing to get the money together. Think about how long it will take you and tell the judge your timeline. Give the judge a reason to trust you by showing your work. Most judges I know will be reasonable if you are able to show them proof of what you're doing. Of course, you need to be realistic. If you show up at the next court date without a lawyer, they're going to arraign you and keep your case moving.