"Can IRA to ROTH conversion be done before completing RMD withdrawal"
No, because that's the law. The intent of IRAs is to create money to use in retirement, not to create tax-free money to pass on to your heirs. That's why there is an RMD requirement in the first place, you must withdraw at least some money and pay tax on it, based on your remaining life expectancy. For the same reason, you must withdraw your RMD first so you can pay tax on it, before you can convert any of the pre-tax IRA to a Roth IRA.
