Use your intuition. You need to gauge from your experience what is practical, to be firm in a discipline without become so rigid that the discipline snaps, leaving you burned out and abandoning the practice altogether.
I recommend in the beginning to practice numerous, but short meditation sessions, so as to gradually build stamina and endurance. You will naturally gravitate towards the practice as you progressively see and feel the benefits in your own heart, perception and experience.
Joyful in hope, suffering in tribulation, be thou constant in thy prayer.
Benedictis, qui venit in nomine Domini. Osanna in excelsis.
"Blessed is he who comes in the name of the Lord. Hosanna in the highest!"