A number of comments on your question:
- You should have notified the Secretary of State of the change in the business structure.
- Since you are changing the structure from a SMLLC (disregarded entity by default) to a multi-member LLC (MMLLC) the default treatment is a partnership for federal income tax purposes.
- You need to read the link provided by @DMarkM1 and focus on the SMLLC section. Based on the limited facts, you will need a new EIN.
- You also need to make sure you have a revised operating agreement.
- You need to make sure that this change in structure follows the guidelines of Revenue Ruling 99-5.
- You don't need to file form 8832, as an eligible entity with two or more owners is by default classified as a partnership for federal income tax purposes; as noted above.
- You should have been able to obtain an EIN online immediately. At this point you will need to wait until you receive it from the IRS. Hopefully you have extended to tax return.
- Your start date is the date the MMLLC began business.
- Your form 1065 is an initial return.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
