Depends on the size of the firm, and how much you interact with them.

A local law office with 1-2 lawyers and a few assistants; likely $1000-1500 that’s held by them to put towards any future requirements.

Larger firms range from $5000-25000 for an individual, but again, usually this money is held in a trust on your behalf and you can use it to pay down any bills or let them keep it and pay the invoices as they come.