>
"how do you know when to stop supplyin gthe sugar syrup?"
>
"...I don't want to leave my frame feeder in forever
"
I think it depends on a couple, or a number of things.
When was the hive first established/set up. Early or late in the spring.
Whether you are starting with all foundation [or foundationless

] or drawn comb. Therefore, feeding syrup to help assist the bees get started building/drawing out comb.
The time [approximate] when you first saw eggs in the new hive or nuc/split where there were previously none or very few; for a new queen for example.
>> And then the appearance of 2-3 to 4 frames of capped brood; a
good solid
"brood pattern" at the end of week two, showing that 100's of new bees will be emerging per day when they are ready.
Worker bees emerge after 21 days from the egg.
Average age range of bees for
first foragng trip is 10 to 25 days from hatching..."
Biology of Honey Bee", M. Winston.
So, about 30-40 days from the egg stage,
new bees will begin foraging.
Whether the colony population is building up normally and no queen problems or delays in build-up.
No unusual adverse weather conditions during early stages of colony growth.
Good colony growth to take advantage of nectar flows for your area.
"..sometimes i pull them off the feed -- to get them to go out and find there own (when good weather and nector is out there) --"
I don't know if having sugar syrup readily available to the bees interferes with their normal recruitment of nectar foragers. I too, like for them to go out and find there own nectar at some point. For a package started first of May, I stop feeding at end of the month,.usually.