It is better to practice LST when the stems are still flexibles so you can still do it but be carreful to not break the strem at his base ( it happens a lot with me for my late lst )
It's also better to practice defoliation during veg / 1st week of pre flower because in flowering she'll could nor recover from a hard defoliation. If you are planning to remove the leaves that are blocking light to lower budsite it's ok , if you air circulation is bad and your humidity is high then it's ok too as long as you'r not over doing it.