Fertilizing

Whats a good solution if only watering plants individually from 550ML spray bottles? I am using plant prod 20-20-20 im thinking about starting to use it this weekend as my plant sprouted on Nov.19 its now into its third week of life standing at about 5.5inches. I was thinking about putting the fertilizer in lightly first like maybe 10-15 ML of fertilizer is this ok??
Also my plant is now working on its fourth set of leaves and the next set is starting to form like always. I am growing some Bubblicious im just wondering if topping is recommended for beginners? If so, can someone help explain the process a little more throughly.
Thanks Again

From what i know, topping is really only beneficial when you dont have a tall enough space to grow in, as it promotes growth horiztonally and not vertical. All you are doing is making the main cola grow into two, but it will not nessecarily give you more or better buds, because the plant has to take in nuts for them both. it also shocks the plants for a few days.