How do I stay in the United States during I-526 processing?

Currently, there is no way to concurrently file for adjustment of status with the I-526 petition, so you will have to leave the United States when your status expires. You may be able to reenter while the I-526 is pending, but with that I-526 immigration petition pending, you may be subject to additional questions by the Customs and Border Protection upon entry.

You need to meet with an immigration lawyer and plan more carefully.

You will be able to apply for a six month extension of your visitor status, which may or may not be granted depending on whether you meet the requirements. But even if you get the six month extension, it will only bring you to September, and it is unlikely that your I-526 petition will be adjudicated by then. So most likely, you will have to leave the country and come back in on an immigrant visa (assuming your I-526 is granted). Good luck.

Since I-526 adjudication is taking 14+ months to adjudicate, there is no way for you to stay in the United States with just a tourist visa that is valid for six months. You can only apply for the I-485 after the I-526 is approved if you are in the United States on a valid visa status. Filing the I-526 is not filing for the EB-5 visa, for which you could apply after the I-526 is approved. If you will start the EB-5 process in January, I would advise that you return to your country and come back with the approval of the immigrant visa application (DS-260).

You cannot remain unless you extend your visitor visa or apply for another nonimmigrant status.

There is no provision for you to stay during the the processing of your I-526. You would have to leave when your stay has expired. If you are in a country that has a visa waiver status you could return as a visitor without much difficulty.

Before your current authorized stay expires in March, you will need another valid nonimmigrant status to stay in the United States. In other words, the filing of the I-526 in January does not permit you to stay in the United States. If you would like to spend time in the United States until the I-526 is approved, you have the option of changing to another status or re-entering the United States anew. This can be tricky, as some statuses and visas are not meant for people applying for permanent residence, so be sure you discuss the details with a good immigration attorney.

You may remain in the United States under the visitor status during the validity period of that entry (i.e., until March). You can also either file to extend your current stay or if you leave the United States and your visa stamp is still valid, you can re-enter the United States as long as you convey to the immigration officer at the port of entry that your intent is as a temporary visitor.

Filing the I-526 application does not confer status to you and even when it is approved, that does not grant status. In order to file the I-485, you must be in valid status so you would have to either extend your B visa or find another visa while the I-526 is pending. If you leave the country after the I-526 has been filed, you could reenter but you run the risk that the border patrol would think that you have immigrant intent and deny you entry. If you decide to try to reenter after the I-526 has been filed, you should bring proof of ties to your home country as well as proof that your visit will be temporary.