Really unless you want cloudiness for weeks or months you should take all the sand out and rinse it in buckets VERY thoroughly before you put it in the tank. Rinse out the tank again while the sand is out too.
If your sand is anything like the "pre-washed" sand I bought at home depot, you definitely need to take it out and rinse. The water i rinsed with was completely foggy and you couldnt see through it until i had rinsed and drained each 1/4 full bucket at least 15 times. After the rinsing when i put it in the tank with water it was almost perfectly clear within about 5 minutes, and tiny particles dont get stirred up or damage the filter.
Yours may not be as bad because you said you got it at a LFS tho.
If your sand is anything like the "pre-washed" sand I bought at home depot, you definitely need to take it out and rinse. The water i rinsed with was completely foggy and you couldnt see through it until i had rinsed and drained each 1/4 full bucket at least 15 times. After the rinsing when i put it in the tank with water it was almost perfectly clear within about 5 minutes, and tiny particles dont get stirred up or damage the filter.
Yours may not be as bad because you said you got it at a LFS tho.

