So if the poppy juice now is in the EtOH, the alkaloids should get dissolved in the EtOH, the duration of this process can vary, but it should be around multiple hours to a few days. After the alkaloids are dissolved in the EtOH, you'd need to filter the solution to remove remaining plant/juice material. Then you could let the EtOH evaporate, leaving behind a purer form of the alkaloids/opium. It might be, that there still be some other compounds, in this case you could re-dissolve the alkaloids in EtOH, filter the solution and let the EtOH evaporate, in order to enhance the purity of the opium.
But you could also use the juice directly, this would have similar effects, since the juice of the poppy is technically just the alkaloids substituted with plant material, so it's like opium but far less pure.