How to get values of T1,T2, T3?

You can calculate them using program.This is a easiest way how to get them.... :-)

This program creates so called include files necessary to compile source code. It is assumed, that you will run calculation program in the same directory, where you have source code.

Accuracy of counter/digital scale with constants after the first calculation is frequently not very high. The reason is, that Xtal real frequency is slightly different from the value on its cup. To get better approximation use program again, but with correction fields used.

Well.... There exist also another way to calibrate device... If you have Xtal for which the source is written (T, T1, T2, T3 and Z values) you should get result close to the expectations. However slight tuning is usually desirable. One way is variation of constants using programs mentioned above. But you can use also another approach:
You can replace one of the condensers around Xtal by capacitance trimmers, say 30 pF (or better set condenser to value 15 pF and add small trimmer...). And than youn can adjust Xtal frequency to proper value. It means that one giving accurate display...