After your attorney files your petition, the bankruptcy court will send out a notice of bankruptcy filing. This goes to all of your creditors and serves notice of the protective order which puts in place the automatic stay.
You will also get a copy of this notice. It includes important information, such as when and where your meeting of creditors is. It will also have your case number on it. You should keep a copy of the notice to provide to any creditor who tries collecting a debt after your bankruptcy is filed.
As a side note, if you have listed any family members of creditors, you may want to consider letting them know before your attorney files to avoid an awkward conversation later.