Hello, it depends on which kind of rics you want, Yumas or Florida's. Yumas drop babies when they multiply and Florida's split. I have Florida's as I much prefer the look of them over Yumas.
I have two rics and the orange one i bought the size of a dime its now the size of my hand a year later. The purple ones have gotten alot bigger since i bought them too. I find that they are slower growing then normal mushrooms but very easy to have in the aquarium and delightfully beautiful too.
I know some people have had issues with MH lights and rics, so if you have them you might have to place them lower in the tank. Mine are under PC lights and doing awesome. My tank is also a 3 gal pico.