There are three distinct shortlisting processes across IIMs: Type A (interest form based), Type B (form + fees), and Type C (CAP - Common Admission Process). Type A includes IIM BLACKI (Bodhgaya, Lucknow, Amritsar, Calcutta, Kashipur, Indore), Shillong, Vizag, and Sambalpur, which send mails to fill a free interest form; shortlisting is based on form details and getting the email does not guarantee a PI call. Type B includes IIM Rohtak, Amritsar, and Mumbai; they release forms with cutoffs and you pay a fee (Rs 2000 typically, though Mumbai dropped fees this year), with nearly everyone clearing sectionals getting a PI call.
Type C (CAP) covers IIM Udaipur, Trichy, Ranchi, Kashipur, Nagpur, Jammu, Bodhgaya, and Sirmaur; they send interest forms for shortlisting and conduct a combined WAT-PI offline this year. IIM Raipur and Sambalpur have exited CAP. For candidates at 98-99 percentile general, fill Type A forms for BLACKI plus Type B for Mumbai/Rohtak/Amritsar.
Skip Rohtak if you don't want to travel there since filling even as second choice can pull you there. Final merit lists start from April end for top IIMs (ABC), mid-May for CAP, followed by Vizag and Amritsar. Check your eligibility at collvera.