I have had clients do this successfully but it will depend on the center personnel. There are no disadvantages but you may not be successful.
I am providing this general advice based on the information given and my understanding of that information. This is general advice . This advice is not intended to give a legal opinion. This advice is not intended to create an attorney-client relationship. I strongly advise you and your husband to contact a lawyer about the specific facts of your situation.
No disadvantages. I think what day u can do a walk in may depend on the local practice of each ASC or application support center. A busy local immigration attorney would probably know the day your ASC has walk-ins.
Like others have said, you can try going in ahead of your scheduled appointment. However, if the ASC is unable to assist you, follow the directions on your appointment notice regarding rescheduling biometrics appointments. The worst thing you can do is not get your biometrics done.