Make the guess a signal (or set of signals) that you input into the function block, and route the outputs back into those. You should be able to initialize them somehow.
I am not sure of the best way to initialize something like this. I know that initialization blocks exist but I have not seen how to use them. I know one way is to use a switch block that would take a constant as one input and the feed-back values as another input and use a compare on the time as the signal to decide which of the two to use. There might be a much better way than this.
