I book touchups only during the week either in the mornings or evenings before / after my bookings, as they typically take very little time. At the moment I do not book touch ups on the weekends.
As a base fee to cover my set up as sanitation prices have risen drastically over the pandemic, I do charge a touch up fee of $25. If you are scheduled to get another tattoo with me, i'll happily touch up your orignal tattoo free of charge.