The target is too ambitious. Even if you have an all-equity portfolio, it will need to generate a yearly return of 15%, which is unrealistic.
Depending on how reliant you will be on your investment to meet your post-retirement needs, create an asset allocation plan with the ideal combination of equity and debt.
An equity-debt allocation of 50:50 is considered suitable. However, do not invest in equities in one go. Rather, spread the money over 2-3 years.
Assuming returns of 6-7% from debt and 11-12% from equity, you can expect to earn annual returns of 11-12% on your portfolio.
With these returns, your corpus would appreciate by 50-60% over the next five years, if not double it.
Given the volatile nature of equity, your investments may fluctuate wildly during this period. Thus, we advise you to stay invested for longer (more than five years).