For those who want to offer a sacrifice, Qurbani rules recommend that once the new moon of Dhul Hijjah appears (i.e. on the 1st of Dhul Hijjah), that they do not remove anything from their own hair, nails, or skin until they have offered the sacrifice. The last day recommended to cut hair and nails is before the new moon of Dhul Hijjah appears.
In the Hanbali madhab, it is considered haram to cut your hair or nails if you’re donating Qurbani. However, according to most scholars, refraining from cutting your hair and nails is a recommended act rather than an obligatory one. It is best to seek advice according to your school of thought.