Choose the filing point by the capital commitment and evidence actually available. There is no fixed E-2 waiting period solely because money came from an estate, but tax, creditor, court or estate-administration restrictions may still affect when it can be released. Ask the adviser to explain the basis for any proposed holdback instead of assuming every delay is optional.
Set decision points, not a promised date
Useful milestones include the executor's confirmation of the next distribution, the transfer of committed funds, the signing of the lease or purchase, and the completion of the source and path record. Processing has no guaranteed duration. Plan for the difference between the visa's validity and the period of stay recorded on the I-94, and keep the intention to depart when status ends consistent with the business plan.
A binding commitment can be important, but the terms, contingencies and financial exposure should be understood before funds are placed at risk. A preferred filing date does not justify presenting a consent, transfer or agreement as effective before it actually is. What is possible is a carefully drafted arrangement in which the only remaining condition on release of the funds is the immigration decision itself.