How and when streams can be split is completely dependent on a couple of different variables:
How many shifts have been worked and uploaded to the app at the time of stream.
Your total outstanding balance at the time of transfer.
If you do wish to try and get a rough idea before making a stream, take a look at your available balance in the app and how many shifts you’ve worked in the current pay period:
If you have worked enough shifts in the current pay period to cover the amount you wish to stream, that amount will most likely be from your next paycheck so will be carried over.
If you have not worked enough shifts in the current pay period, your stream will most likely come from the paycheck coming up soonest.