I use to clear a bowl of 40x and just go into hyperspace. The stuff is physically harmless but I'd still recommend starting low. Is your product dry? The stuff I got burned so quickly I just tried to get it in one big hit out of a pipe. I would say pack a small amount and try that and then go from there. I always felt that with salvia, if you try a little bit, you'll know where thats going to take you when you try again, change the amount based on the amount.
Flickering is right btw on the reverse tolerance, salvia has some odd properties.