First, be careful of franchise rules that require citizenship or permanent residency for their investors (that is, you'd be making the investment before obtaining permanent residency). Second, you have to have invested or be in the process of investing, but that generally has resulted in the investor placing the entire amount of the investment into an escrow account, to be released upon I-526 approval.
The business plan and other legal documents may clearly show all the required investment are available in escrow to be committed, while some of the investment funds will be committed at time of filing the I-526 petition while the balance may be committed at time of the approval of the I-526 petition.