I am planning to set aside <$500 per month for investing. Considering that i am buying SWRD. Is it better to invest lump sum (quarterly) or monthly? Is IBKR or SB a better option ?

Hi, I am not sure what is SB. For IBKR, the monthly cost is USD10 and each trade cost usd $1.05. You can offset the $10 with trade. It is the cheapest broker to start buying ETF on monthly basis. Set up is pretty simple too.

Similar to what other has mentioned, do dollar cost averaging.

Its always advisable to invest consistently monthly to average out the cost price of your stock.

Dollar cost averaging works.