Anytime during the pre-rut or rut most types of calling will work well. During the pre-rut rattling works especially well because bucks are sparring to figure out hierarchy. During the rut rattling still works, and so do most grunt calls. towards the end of the rut using a doe-in-heat/ fawn bleat can work if their are lone bucks in the area. Mature bucks that have seen several breeding seasons know that a doe will sometimes lose her fawn on purpose to be bred by a buck, so a lost fawn bleat will tell a dominant buck that there's a doe out there that he should be on top of. Pun intended.
The key to remember with calling deer is that it works well in areas with an equal buck to doe ratio, and even better in an area where there are more bucks than does. This is because they have to compete for females. In an area where there are way more does than bucks, calling will work less, and may not work at all.
As long as your calling sounds realistic, does & sometimes bucks will come in just out of curiosity.
So good luck, and post some pictures when you score!
Cheers.
Tim H