score:1
Not quite sure what the question is.
You could book a tourist trip to the USA and ask for a visa for that.
If you want to wait till April 20th after you get the ticket you need to check the wait times to get a visa interview appointment and the processing time. I checked for Chennai and it's a week to appointment and one working day to get a visa. Delhi is only 2 days longer. Aka you have enough time.
Or are you asking whether you will be given the visa just for that? We can't answer that. Attending a conference is a perfect reason for a B1 visa but whether you have enough ties and funds is something only they will decide.