How fast is concurrent filing from an H-1B visa?

If the H-1B was timely filed you protected under the 240-day rule. After that you need to stop working or premium process your case.

Once your I-485 is on file then you are in a period of stay authorized by the Attorney General but can’t legally work again until the interim work card (Employment Authorization card) is issued. This is typically requested with the I-485 submittal if you sent both the I-526 and I-485 together.

The processing times remain the same whether your visa is expiring or not. Although a pending Adjustment of Status (U.S. Residency, Work and Travel permits) application is not considered having status, you are protected while it is processing as long as it is filed before your current H-1B visa expires. You did not specify which type of EB-5 Visa application you will be filing and which type of investment you will be making therefore I can't provide you with time estimates, but generally, Rural (Set-Aside) EB-5 (Indirect) Visa applications are being approved the fastest, some of them are approved in under 1 year.

The processing depends on whether you requested regular or premium processing. Premium processing requires payment of an extra fee, but USCIS will process your case within 15 calendar days. If your H1B was filed before the expiration of your current status, you may remain in the U.S. after your status expiration during the pendency of your H1B. However, if your H1B is denied, you will be required to leave the U.S. immediately.

Concurrently filing I-485 when you are under H-1B does not speed up the processing of your I-485. Once you have filed your I-485, you can still legally stay in the U.S. even after your H-1B expires. However, if you can still extend your H-1B, I would suggest you do it because H-1B allows dual intent. In case your I-526 or I-485 gets denied, you can still keep your H-1B status in the U.S.