Setting the valve lash can be done in many different ways, set with the piston on the firing stroke at top dead center, setting the intake valve when the exhaust valve rocker arm starts to open and then rotate the motor over until the intake valve opens all the way and start to close to set the exhaust lash. Some people, racers, shade tree and professional mechanics will remove the distributor cap and bump the motor over by hand so the rotor is pointing at the spark plug wire to each cylinder and set the valves that way
As already pointed out about setting the lash cold or hot will come into play depending on which head type you have, iron or aluminum.
I would start with cam makers suggestions on the lash and then experiment to see if you want and like them tighter or looser when hot
I use to run a 1970 Cuda in NHRA stock, it was very sensitive to the lifter preload, same thing on the 1969 Hemi GTX we raced before the Cuda, it was very sensitive the hot lash settings. We where running cheater cams that would check okay in tear down so they where not stock cams
On your roller cam it may want, or you may like it with tighter or looser lash, only you will know what you like and keep