As long as the provider has the patient's signature on file at their office, you do not need a copy.
As far as when to receive the patient info it is really up to the provider. Some like to get all the info together and give it to you up front. Some would prefer to give it to you as the patients come in. There is no right or wrong, it's whatever works best. Sometimes it is easier for you to get the info in advance so you can get some of the data entry out of the way, but I wouldn't make it a necessity if they provider feels it would be too much extra work at the beginning.
Michele