Can we perform Kumbabishekam in the month of AADI

If you are going strictly by the almanac then it would not be easy to disobey the priest as he is not telling anything from his side and only suggesting what the almanac says. Let us first understand a bit about the Aadi month and the reason of not doing some auspicious activity during this one. Aadi is the fourth month as per Tamil calendar and coincides somewhere in part of July to part of August. Scientifically, it coincides with the starting of southward movement of Sun.

Traditionally, it is believed that Aadi month is an inauspicious time and that is why people avoid marriage or big celebrations like that during this time. Aadi month is considered as the night time for the Devas (Gods/ Demi Gods) and it is thought they are taking rest during this time and if we pray them then they would not be listening to us and our prayers might go waste. At the same time there are many festivals and celebrations which are done in the month of Aadi and they are of general nature rather than the individual celebration. Kumbabishekam ritual is performed once in 12 years according to Agamas (religious treatises) and by sprinkling the holy water on the deities through the temple tower. This process is supposed to recharge the spiritual and religious powers of the deities and is an important activity.

In many of the religions there is always a solution to a problem in adverse conditions. The religious rules and regulations are there to follow in the normal times. In the time of calamity God also knows that we are doing it under a compulsion. So in such times the priest would find out some way because in our scriptures there are many things mentioned for the bad times and it is no surprise if some of the stringent rules are compromised under those observations. For example in our old scriptures it is clearly mentioned that when we visit an alien place then we should not restrict our food habits and what ever is available in that country we should try to make our choice from that only. Accommodating rules with practicalities of life would lead to workable solutions.

So, you can talk with the priest and he would definitely come up with a practical solution in this Covid-19 situation. He would like to move these dates slightly this side or that depending upon the exact Muharatham. Let him work out on that. Tell him that it is being done in utmost urgency and if required a mini ritual can again be executed later if that helps to ratify the ill effects of this one.

This year as per our Telugu calendar, Ashada Masham which is the fourth month in the Telugu calendar is moodha Masam and no functions are allowed at this time. So it is not acceptable to perform any temple function also in that month.
Even in Tirupathi during Tamil Adi month no activity will be performed. So I think it is better to perform the function before adi itself. Please ask your priest to bring the function a little forward and decide the dates as per his suggestion.
Some adjustments are to be made in performing the function and you have reduced the gathering numbers and follow the rules laid down by the government for performing the events in places of worship. Then you can perform the same and I feel that will be the best solution for your problem.