Help! How to properly DCA or PCA stocks?

Hello! I just need advice or guide on how to properly cost average on stocks. To put it simply, how do you manage your buying monthly.

I am allocating Php 20,000.00 monthly for my investments and I spread it to mostly 10k for REITs and 5k for Funds and I’m using DragonFi for all of that. The remaining 5k is for MP2.

My question is how do you budget your monthly allocation when buying stock or reit while considering the board lot of each one?

Thank you!