SIP- Systematic Investment Plans are ideal for investing in the stock market. There is generally no guarantee that the price you bought at a particular month was the best or lowest, and so monthly investment allows you to average out and get perhaps the best deal. One should always see if they have surplus funds ready to invest and if so add the extra whenever they can to increase the portfolio size based on the planned allocation. No one should be given anything more than what was planned unless of course the plan changes due to new opportunities that may have emerged.