In answer to your question we will have to analyze the timeline of the EB-5 process for you obtaining conditional permanent residence. The EB-5 process will involve the first step for you as the foreign national investor filing the I-526 petition with the USCIS. The process of adjudication by the USCIS of the I-526 petition may take several months, more or less. The filing of the I-526 petition does not authorize you to stay in the United States during the I-526 process. After the filing of the I-526 petition and you may enter into the United States as a B1/B2 visitor, with the intent to stay for a temporary authorized period of stay and then have the intent to leave the United States and return home. Your B1/B2 temporary authorized period of stay may only be for six months. That is, authorized B1/B2 stasis in the United States will probably be less than the time it takes USCIS to adjudicate the I-526 petition. You may request an extension of B1/B2 status for an additional period of temporary stay, however the B1/B2 petition for extension will ask if you had filed an immigrant petition and in this case the answer would be yes. The USCIS may not extend your B1/B2 status for temporary stay as your filing of the I-526 petition may indicate an immigrant intent which may not be consistent with your temporary intent and your application for extension of B1/B2 status United States. However, if you are visiting the United States under B1/B2 status for an authorized period of stay and if during this period of time the I-526 petition is approved you may file an application for conditional permanent residency with the USCIS so that you will obtain your conditional permanent residency while in the United States.
You can file an I-526 EB-5 petition while on a B-1 or B-2 visa. However, since most EB-5 cases take 1 ½ to 2 years to process, you will need to return to your home country for Green Card EB-5 processing because the most you can stay in the US as a visitor is 6 months with a possible up to 6 month extension.
Since the EB-5 visa is am immigrant visa, obtaining a non-immigrant visa – which requires you to show and prove you intend to leave the U.S. – would be difficult. However, if you have a longer-term nonimmigrant visa you could be able to remain in the U.S. while the I-526 is pending.