Okay I've looked at this a lot trying to figure out what to do and I still think process flow is probably the best for this. It shouldn't affect your other logic at all and it most closely matches what your source is currently doing.
I tried doing it 4 ways in your model, initially I thought the hourly rates was actually setting the inter arrival rate so I experimented with using a global table, I quickly realized that it wasn't setting the rate but just making that many items evenly spaced over the time frame. You can make a schedule source in 3D space too and I tried that (the middle queue in the model I'll attach) but the issue is it doesn't repeat every day and it just dumps them all in at the same time. I then decided that the schedule source was still the best option for 3 reasons: you can set the schedule to repeat, you can customize the time frames really nicely, and you can set when you want the items to come in the time frame (right at the time, evenly spaced, or randomly).
Here's the model that has my experimentation:
mk-simulation-with-fp-in-minutes-demo.fsm
You can see all the sources and you'll notice that they all look really similar. Here's a model with just the schedule source in process flow:
mk-simulation-with-fp-in-minutes-finished.fsm
Does that perform how you'd expect?
