<prompt> Human: Lets assume that my IRA, 401k, retirement accounts etc are all maxed out and I still have money left over that I should be investing. Everyone recommends SP Index funds, but when exactly should I purchase? x200B;I know everyone says that you cant time the market, so would it be best to simply purchase x amount every month on a specific date and stick to that schedule? Or should I just save up in cash and make larger investments at once?  <response>: Index fund, set amount every month 