Meditation is essentially a moment of relaxation, so it should be done at your convenience. Pick a time when you know you won't be interrupted and when you feel free to relax and enjoy.
A good time to meditate is before meals. If you meditate after eating, you may fall asleep. However, do not force yourself to meditate if you are very hungry, you probably spend the entire meditation thinking about food. If so, you can meditate after two hours of eating.
Doing stretching exercises before sitting down to meditate helps good circulation, takes away inertia and agitation, and makes your body feel lighter, so you will be able to sit quietly for a longer time.
This is a preparation for easy meditation. Deep breaths in and out, as well as doing Nadi Shodhana Pranayama (alternate nostril breathing) is always a good idea.
This practice helps to calm the rhythm of breathing and brings the mind to a peaceful and relaxed state.
You can tell the difference. A gentle smile throughout meditation keeps you relaxed, peaceful, and intensifies your meditation.