Hilchos Nezirus 8:9

Let’s say that a nazir shaved when his burnt offering and peace offering were brought, but they were slaughtered with the intention of other offerings. In such a case, his shaving is invalid and his offerings don’t count.

Hilchos Nezirus 8:10

If a nazir shaved when he brought his three offerings and one of them was valid, then his shaving is valid. He then brings the other offerings again and offers them properly.