Typically we'd suggest 12-14 hours a day for light/UVB/heat, plus some night heating if your house is too cold (under 65 at night for an adult Russian and under 60 at night for a hatchling is my threshold opinion for night heat). You can choose whatever hours you like, such as to correspond with when you are awake and plan to feed. Many tortoises will get up soon after the light goes on. You can get a digital timer for $10-15 (I suggest a grounded one).
Russian tortoises, along with most Mediterranean tortoises can take temperatures much colder than 65 degrees at night. They should have at least a 15-20 degree drop in temperature from their daytime to night time temperatures.
Keeping them consistently too warm, along with other factors almost always results in accelerated growth rates.