No, doing a two‑day fast (be‑upvās / attham) before starting Varshitap is not compulsory according to Jain śāstras.

In practice:

• What is essential

- Take proper saṅkalp (vow) for Varshitap from your guru / sadhu / pandit. - Follow the alternate‑day fasting pattern (or the pattern your tradition gives). - Observe samayik, pratikraman, japa, svādhyāy, and good conduct (ahimsā, satya, brahmacharya, aparigraha).

• What is optional / local tradition

- Some gurus or local upāśray/mandir may recommend: - 1–2 days of upvās, - or a few days of āyambil / ekāsan, as a preparation or “trial” before starting the full Varshitap. - This is for your health, discipline, and readiness, not because śāstra makes it a strict rule.

• Best approach

- Since Varshitap is a very strong tapa, decide only: - after checking your health, and - after taking clear guidance from your own Jain guru / pravachankar, and then follow their vidhi exactly.

You can read a simple explanation of Varshitap and its vidhi here