When i did my training i was told not to do it before 6 weeks as it can over process the lashes, frizz and damage them. But you also should wait for the clients lash cycle aswell.
I use lash base lash lift products and cant fault them at all. In the salon i work in she uses salon system and some clients have mentioned they have dropped quiet quick. But to be honest they wont stay as upright as they were when they were done as your lashes will be growimg out anyway.
Lash base come in sachets an salon system use little pots. Another therapist mentioned to me, which makes sense, with the bottled products once you have broke the seal and opened them they will become less an less affective as time goes on the more an more you let air get to it....which would kind of make sense if the clients lashes arent holding out an your only, say, half way through a bottle?.
As much as the sachets are a pain, i can sometimes get 3 clients out of 1 sachet, ive not had one problem with clients lashes dropping, however, in the salon i work in who use salon system. We have had a few clients say they have not lasted aslong as it shouldve xxx