Derby,
Once they shoot a bine above ground they will take off quickly. As soon as they are tall enough to reach some twine you should cut the plant back to the 4 healthest bines and start training them onto the rope. Depending on the strain they can get extremely tall pretty darn quick too. So dont hesitate and try not to be too rough with the bines the entire first yesr, After the firdt growing season in the ground you can start planning the brews you wish to nake and ibsure that you have enough hops to complete the recipe unimpeded or without any signifcant slowing in your growth. My second year hops are all still alive and I am waiting impatiently to go to the garden and hoe/weed as soon as the seeded bines come up so I know exactly where to aoid with a shovel or a hay rake. I truly enjoyed growing my own gops last year so it should be a snap this season too, It should be a matter of trimming off any dead wood laying on the ground, and train the bines onto the twine and sit back and wait. You should plan to train the bines every week as a minimum. Also plan to water them everyday early of mid day to avoid fungal infections that pop up spontainously in what ever you will be using as a boil and mash tun. Good luck on your entry to home brewing and I also hope that you find all the answers you need for a great job rather than a Mediocre attempt at home brewing.
Wheelchair Bob