The first two years I filled the tank with fresh water added 1/4 tank (or so) of outside water several weeks prior to bringing in koi, but then had to wait for water temp to equalize when I brought in koi.
So for 2011, I pumped in water (water temp 38) from the pond thru the basement window into a empty tank, netted my koi (4 @ 15.5"-16") hauled in some media from the bio filter, dropped in a airstone, covered up the top of tank so it will warm up slowly and was done fairly quickly. I'll wait a couple days for the water to warm up before I run pump thru filter & bio filter.
About the only differance this year is I built a slightly larger bio filter 'cause I accidently busted the old one. I might go larger pump this year, will see. I used low protein food last year for the first time.