i always check at the gas station.. i wait until im finished fillin her up so its been sitting for 3-4 minutes.. i notice a big difference between when i check as i pull in and after refueling
slightly off topic..
i was thinking about this the other day.. i wonder how much oil i lose just from checking the oil every 250-300 miles because i always pull out the dipstick, wipe it clean, and check it again.. and usually just out of habit wipe it clean again