As soon as you are eligible. After you marry and file the 485 and 765 and you receive either your residence or work permit you will be able to get a SS number issued. With your SS number and either EAD or GC you will then be able to get a DL issued by the Texas DMV.
The answer provided is general in nature and should not be construed as legal advice as not all facts are know by the attorney, nor does the answering of this question create an attorney client relationship.
After having gotten married and filed for I-485 adjustment of status and having obtained your employment authorization card, you'll be able to apply for an SSN and a state ID.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.