Begin by exporting the data from Whisky Hunter. Depending on the platform's capabilities, this might be done through a built-in export feature. Typically, you can export the data in CSV or JSON format. Ensure you have all the necessary fields and data elements you want to transfer.

Set up your local environment to handle data transformation and upload. Install Python and any necessary libraries, such as pandas for data manipulation and the Google Cloud SDK for interacting with Firestore. Use `pip` to install these libraries:
```bash
pip install pandas google-cloud-firestore
```

Use Python to read and transform the exported data into a format compatible with Firestore. If your data is in CSV, use pandas to convert it into a dictionary format, where each entry corresponds to a document in Firestore. Here's a basic example:
```python
import pandas as pd

# Load data
df = pd.read_csv('whisky_data.csv')

# Convert to dictionary
data_dict = df.to_dict(orient='records')
```

If not already done, create a Google Cloud Project and enable Firestore. Go to the Google Cloud Console, create a new project, and enable the Firestore API. Set up a Firestore database in Native mode for optimal performance.

Authenticate locally to access your Google Cloud resources. Use the following command to authenticate:
```bash
gcloud auth application-default login
```
This command opens a browser window for authentication. Follow the prompts to complete the process.

Write a script to iterate over the transformed data and upload it to Firestore. Use the Firestore client library to add documents to a specified collection. Here’s a basic script outline:
```python
from google.cloud import firestore

# Initialize Firestore client
db = firestore.Client()

# Define the collection in Firestore
collection_name = 'whiskies'

# Upload each document
for record in data_dict:
db.collection(collection_name).add(record)
```

After uploading, verify that the data is correctly stored in Firestore. Use the Firestore console in Google Cloud to browse the collection and check that all data points are present and correctly formatted. You can also write simple queries using the Python client library to ensure data integrity.

By following these steps, you can successfully move data from Whisky Hunter to Google Firestore without the need for third-party connectors or integrations, fully leveraging Google Cloud's own tools and libraries.