A full-day tour from Delhi to Mathura and Vrindavan allows you to explore the historical and religious significance of these two cities, which are closely associated with the life of Lord Krishna. Here's a suggested itinerary for a one-day Mathura and Vrindavan tour from Delhi:

**Morning: Departure from Delhi**
1. **Early Morning Departure:** Begin your day early in the morning, ideally around 6 AM, to have ample time to explore Mathura and Vrindavan. You can hire a private car or join a guided tour that includes transportation from Delhi to Mathura.

2. **Breakfast:** Stop for breakfast at a restaurant on the way to Mathura.

**Late Morning: Arrival in Mathura**
3. **Mathura:** Arrive in Mathura, the birthplace of Lord Krishna. Visit the following places in Mathura:
   - **Shri Krishna Janmabhoomi Temple:** This temple is believed to be the exact birthplace of Lord Krishna. It is a significant pilgrimage site.

4. **Vrindavan:** After exploring Mathura, head to Vrindavan, which is about 10 kilometers away. In Vrindavan, you can visit several temples and sites associated with Lord Krishna:
   - **Banke Bihari Temple:** One of the most famous temples in Vrindavan dedicated to Lord Krishna. The temple is known for its unique black idol of Krishna.
   - **Iskcon Temple (Sri Krishna-Balaram Mandir):** This temple is associated with the International Society for Krishna Consciousness and is a beautiful place to learn about the teachings of Lord Krishna.
   - **Prem Mandir:** A relatively new temple known for its stunning architecture and beautiful light and sound show in the evening.

**Lunch Break**
5. **Lunch:** Have lunch at a local restaurant in Vrindavan.

**Afternoon: Continue Exploring Vrindavan**
6. **Radha Raman Temple:** Visit this historic temple dedicated to Lord Krishna. The temple is known for its devotion to Lord Krishna and his consort Radha.

7. **Other Temples and Sites:** Explore other temples and sites that interest you in Vrindavan, such as Radha Damodar Temple, Radha Gokulananda Temple, and Nidhivan.

**Evening: Return to Delhi**
8. **Return to Delhi:** Start your journey back to Delhi in the late afternoon, ensuring you leave enough time to get back to the city before nightfall.

9. **Dinner:** Have dinner at a restaurant in Delhi or on the way back.

**Late Evening: Arrival in Delhi**
10. **Arrival in Delhi:** You will arrive back in Delhi in the late evening, concluding your full-day Mathura and Vrindavan tour.

Please note that this itinerary can be adjusted based on your interests and the tour package you choose. It's advisable to book your tour in advance and consider hiring a local guide in Mathura and Vrindavan to enhance your understanding of the religious and historical significance of these places. Be sure to check the opening hours of the temples and any COVID-19 restrictions in place at the time of your visit.