Unless you know something to the contrary, I would suspect that if you entered the Vanguard transfer as a one-step transfer (mutual fund to bond VBTLX), then you are vested in the bond fund immediately upon your shares being removed from the mutual fund. Another words, it doesn't take two days as you are surmising, but happens at the same time, same day.
Here, read this, that explains the process at Vanguard. And fwiw, I have transfered between funds many times at fund companies, including vanguard, and it happens simultaenously.
(Edit: I would definitely call them first thing in the morning and explain your situation and see what your options are). And my google search is giving me conflicting answers, but the first answer I got is as follows: (but again, it is AI generated and not consistent):
"Yes, at Vanguard, when you transfer from a mutual fund to a bond fund, the bond fund shares are typically purchased the same day as the mutual fund shares are sold, as long as the transfer request is made before the market closes (4 p.m. ET).
Here's a more detailed explanation:
Transfer Process:
When you initiate a transfer from a mutual fund to a bond fund, the first step is to sell the shares of the mutual fund you're transferring from.
Settlement Fund:
The proceeds from the sale of the mutual fund shares will be available in your settlement fund within your account.
Purchase of Bond Fund:
Once the mutual fund shares are sold, you can immediately purchase shares of the bond fund you're transferring to, using the funds in your settlement fund.
Timing:
If you request the transfer before the market closes (4 p.m. ET), the transaction will be executed at that day's closing price. If the request is made after market close, the transaction will be executed at the next business day's closing price.
Example:
If you request to transfer from a mutual fund to a bond fund before 4 p.m. ET, the mutual fund shares will be sold, the proceeds will go into your settlement fund, and you can then purchase the bond fund shares on the same day."