UDF for finding a flow time where a condition is met
 

Hello All,
I am trying to write UDF for post-processing and DOE. However, I don't write them too often and newer from the scratch so that's why I post this question. I am somehow familiar with C abut I work mostly with Python.
Below the problem description.

I run transient state heat-transfer analysis. What I am interested in is a time point (flow time) at which a maximum temperature at a given (named) face is reached for the first time. The logic of the function should be something like this:

time_point = -1
if T>1000 and time_point<0:
time_point = flowtime

Do you have any ideas what would be the best approach to this UDF? Or maybe there is another way to do this?
So far I am able to do it manually by exporting the face monitor data and post-process them outside FLUENT but i would like to have it as a results parameter.

Thank you in advance!