I have a flow hive but have a brood box then a second brood/super, then the flow hive

new to bee keeping in north east victoria.
both the brood box and the second bos nearly filled out, i have added the flwo hive on top with the queen extractor. is this correct

sounds about right to me! There is a long litany of stories about the bees not taking to the plastic frames (including my experience). This can be mitigated by rubbing bees wax into the flow frames - either bur comb from the hive or (as in my case) bees wax that I ordered. There are plenty of threads on this topic in the forum.

A new colony with two deep brood boxes has a lot of space another deep on top may not get worked in the first year.

When you think of a new brood box/ conventional super it is essentially empty space the bees build out at their own pace. Where as a Flow Super has a lot of surface area the bees need to explore and prepare, so they really need a strong population to allocate bees to this task, otherwise it can see delays as the bees just go on using the space they have and leaving that space unused. Keep an eye on the colony and how they progress, ultimately it depends on them too and if a nectar flow comes in they might well be away.

What you don’t want to do is leave the Flow Super on for weeks and weeks even though it still isn’t being used. Keep an eye on their progress.

Adding some of the colonies own wax to the Flow Frames can be good but you dont want to stretch a population thin.

You can spead up the process starting with one brood box then adding the Flow Super and once they have filled this add the second brood box between. The bees will then have filled the Flow Frames and have honey to build out more comb in the second brood box and expand, again it is really going to be bee population specific.