I have a broody hen but I want her to raise a chick soon

[Sobek]

I want her to raise a chick but I'm not sure if I want to buy the eggs and secretly replace them or if I want to artificially inseminate her... How long can I let her lay on the eggs till then? She seems so happy and I want her to raise a chicken because it breaks my heart how dedicated she is to try and sit on the eggs

 

[ChickenCanoe]

?
Do you know how to artificially inseminate? Do you know how to extract the semen from the rooster?
Do you have a rooster to get semen from?
If you have a rooster, the hen has likely already been inseminated and eggs are fertile.
It is possible to artificially inseminate but if she is already broody, she isn't laying eggs so you won't get fertile eggs till long after her broodiness is over.

Buy fertile eggs as quickly as you can. In Florida, you can probably find fertile eggs locally. Try Craigslist. You can pick them up tomorrow.
https://orlando.craigslist.org/search/sss?query=fertile hatching eggs&sort=rel
Any she hatches will likely be 50:50 males to females.

 

[Pork Pie]

Depending on how frequently she or any other birds in your flock go broody - are you going to feel sympathy for them all, every time? Do you want or need many birds? - do you have room for them? As mentioned above, what are you going to do with any unwanted cockbirds?

Personally, I would assess and reflect on my flock keeping objectives as a priority over a broody hen. Thankfully, we are all different and no decision is the correct one. I wish you all the best with your hatching plans.