As for not tinting for 24 hours after the lift - it's such a tough one. Everywhere else around me offers a lift/perm & tint together, so if i was to refuse someone a tint until 24 hours after their lift they would simply book somewhere else!
I do the ift and tint together (against training instructions) and have never had any problems. I also learnt lash perming 6 years ago as part of a cosmetic make-up course and was taught then it was fine to tint straight after. Different colleges/training providers = different instructions!
Good luck x x