Really depends on what potting compost you have used and even what minerals are in your irrigation water. With probably nobody else growing these near you you will either have to follow someone who seems to have similar conditions - same potting mix, for instance - or actually have your materials tested for mineral content. Otherwise you may have to find your own way. There won't be one fertilizer that everyone everywhere can use because it's the same species of plant. This being a conifer there might be a case for trying to get by on something mild like fish, however either enough N (or whatever) will be provided for a particular potting mix and watering situation by a particular product or it won't. Conifers need nutrients too, yellowing specimens of conifers in pots (and gardens) are common here where I live, where N is the most commonly deficient major nutrient.
A slow-release, low phosphorus fertilizer in combination with a foliar fertilizer is what is recommended by the propagators. I always prefer organic sources if possible, as there is less chance of burning.
Liquid fish fertilizers are commonly stabilized using phosphoric acid, making them questionable for use on many southern hemisphere plants. I'm not sure how definite the wollemi experts are in saying "low phosphorus" but if it is indeed sensitive, the fish will have to be used sparingly, having a "P" level of around 3 on the products I've seen locally.
Bare in mind that plants from Australia survive on very nutrient deficient soils. We are advised not to feed natives normal fertilizers etc. There is a purpose mix that we can get. Probably minimal natural fertilizer would be good. A bit of bone meal (blood and bone) is always reasonably safe. Given the area the pine came from I would be very cautious with the overfeeding. Liz
