Answer

Yes, you can do Aambil, but the pachchakkhan related to Aambil is traditionally taken in the daytime, not at night.

For Aambil, the main rule is to eat only once in the day, with very simple, tasteless food, according to the accepted discipline of your tradition.

Explanation

In Jain practice, pachchakkhan is a vow or resolve taken with awareness and discipline. For food-related vows, it is generally connected with daytime conduct because Jain food discipline avoids eating after sunset.

If you want to do Aambil the next day, you may:

• Mentally decide at night that you will do Aambil tomorrow.
• Take the formal pachchakkhan in the morning, according to your family/tradition.
• If available, ask a Jain sadhu, sadhvi, or knowledgeable shravak/shravika for the exact wording and method.

Spiritual Understanding

Aambil is not only about food restriction. It is a practice of control over taste, simplicity, and detachment. The purity of intention, carefulness, and following proper Jain discipline are very important.

Takeaway

You may decide at night, but it is better to take the formal Aambil pachchakkhan in the morning as per Jain tradition.