You can get an eVisa, it takes 1-2 days to be processed and you get an e-mail confirming it is granted, you won't be able to depart until you get that. If you apply now you might get it Monday morning (Indian time, late night Sunday in US East Coast), but not guaranteed, I find that they tend to be issued around 8am Indian time, though recently I've receive some at other times, as well. I'm not sure how the weekend factors into them being processed.

https://indianvisaonline.gov.in/evisa/

Note that you need to apply 4 or 5 days before you arrive, but it's valid immediatley once issued, so just select the earliest possible date that you can select even if you will end up arriving sooner (I've done this, not an issue)

(I am a South African citizen and have travelled to India approximately 40 times in the past 8 years, including the use of the eVisa approximately 8 times (most recently I entered India on such a visa two days ago and have used eVisa to enter India 5 times since August).

IMPORTANT: ONLY APPLY FROM THE URL ABOVE. There are tons of scam sites which look virtually identical to the above, but they charge you massive inflated fees, and more importantly if they offer or advertise any form of expedited service: there's no such thing