No it's based on ltcg outgo and hence a lump sum payment, preferably in the month of July
Assumption: 9L to be paid
Axis Magnus: option 1
Full payment in July
25000 ER Milestone
54000 ER for 9L
Net value of ER as Amazon Pay voucher: 15800
Axis Magnus: option 2 (if possible)
1L in June and 8L in July
25000 ER Milestone for June
25000 ER Milestone for July
54000 ER for 9L
Interest lost: 625 (for June prepayment)
Net value of ER as Amazon Pay voucher: 20175 (after accounting for interest loss)
Axis Magnus: option 3 (if possible)
1L in May, 1L in June and 7L in July
25000 ER Milestone for May
25000 ER Milestone for June
25000 ER Milestone for July
54000 ER for 9L
Interest lost: 1250 (for May prepayment) + 625 (for June prepayment) = 1875
Net value of ER as Amazon Pay voucher: 23925 (after accounting for interest loss)
Axis Reserve
Full payment in July
67500 ER for 9L
Net value of ER as Amazon Pay voucher: 13500
If you can do pre-payment and split of taxes, I'd suggest
Axis Magnus: option 3 (if possible), with a split of 1L + 1L + 7L in May, June, July
You lose about 625 per month as interest (assuming 7.5% pa) by prepaying 1L but you gain 25K ER points which in the worst case is worth 5K rupees in terms of an Amazon voucher