أَجْزَأَتْهُ النِّيَّةُ مَا بَيْنَهُ وَبَيْنَ الزَّوَالِ.
Translation: An intention made between morning and zawal is sufficient for him.
Quduri literally says the intention is effective between morning and zawal. This wording should not be casually translated into permission to delay until just before the local Dhuhr prayer.
Later authoritative Hanafi commentary prefers a stricter boundary: before the midpoint of the legal fasting day. It is best to intend before dawn rather than rely on the last permissible moment.