Something basic is missing from the question, which is the assumption that only one result will come up when the user types the word. If there is only one possible result, then your question as it is applies and is a good option, specially if the form is long.
But if there are more than one possible results, then you should add an intermediate step asking the user about whom, exactly, he want the info to be used. Once the user select the right person, then you can use that information.
In the scenario where you have more than one option, don't do the process in two steps, first asking about the right person and then if the info should be used, or viceversa. Use only one step with a wording like "if you want to use the autocomplete feature, select the person whose information you want to use, other wise, click/tap cancel".
This is a reasonably good option, and is something used on other systems/apps, so you can use it without worrying at all. Just remember to set it correctly, contemplate options, use the right wording and consider that the user may answer no and type the info himself.
Personally, I prefer the one with one more step, giving the chance to the user to look for somebody on the database or go straight to the form. I think it's always more clear an less prone to misunderstandings.