You can gather identity, beneficiary and available asset records while the estate is being administered. Investment and filing decisions need the actual ownership and funding position, so anticipated probate completion is not an immigration guarantee.
Track legal and banking milestones separately
List outstanding estate approvals, distributions and any asset sales. Ask counsel to assess proposed commitments against the evidence available at filing. If financing is used before distribution, document it as financing with its own terms.
Continue family planning cautiously because estate completion, petition adjudication and visa availability are independent sources of uncertainty. Track the legal and the banking milestones separately, since an estate can be legally resolved long before the money moves and occasionally the reverse. On the legal side the milestones are the grant, the ascertainment of assets and liabilities, the settlement of any claim or dispute, and the executor's readiness to distribute.
On the banking side they are the transfer instruction, the movement of funds or assets, and their arrival in the investor's own name. Preparation of the source history can proceed alongside both and generally should, since the deceased's own acquisition history is the slowest element and is knowable in advance. Avoid treating an expected distribution as available capital, and avoid committing to any timetable that assumes an administration will conclude by a particular date.