So, a very few people asking about japa:
The japa of 1.25 lakhs can be completed in around 2 months at 21 malas a day.
It will take around 2 hours for medium length mantras and reasonable umampshu method.

This japa of 1.25 lakhs is repeated 3 times in a course of a year with gaps of 2 months in between each 1.25 lakh krama.
In 3 years, at this rate, 9 lakhs japa is completed.

The main issues which will arise:
1. To eat less and to somehow reduce heat in the body,
2. To avoid disease during the 9 lakh krama.
3. To slow down the effects of the karma you are burning.
That will cause you some problems, for that graha homa may help.