Lots of ways to get from FW to Poly...
Here goes...
Of course, it depends where in FW you are... it depends on how much fun you want to have to get there.. (or if speed is a factor)
You can go from your site to Pioneer Hall on the internal bus system. Walk over to the waterfront and take the boat to the MK. From the MK , you can hop on the monorail over to the Poly. VERY easy. How long? Oh, that depends on the time of day etc. I'd say... with no crowds, 30 -45min. (maybe even less)
Or you can take the internal bus to the Outpost and then pick up a bus to the MK entrance. From there, you can take a bus to the Poly or again, pick up the boat and take it over to the TTC where you can walk to the Poly. I think this would take longer due to the number of busses and waiting for them.
There are a few other ways but all will take time. But if you are new to this, I would plan on 45 min for sure..more if you run into closing time at the MK.
Hope this helps.
Kris