Have the leaves started to get darker? That would be a sign of nutrients building up, which if you maintain previous levels of fertilization typical of vegetative phase will likely happen at some point in flower... There are enough variables to make each garden a bit different as far as how this all plays out over time.
Consistency in your methods and products you choose to use makes adapting a fool-proof process from seed-to-harvest easier. If you haven't mapped it out, i'd suggest more of an observe and react method, initially. Taking notes along way of the timing of various reactions and adjustments to how the plant is growing or what symptoms it is displaying etc... Then you take that infor and form a plan to preempt what you saw in the last grow and avoid any problems before they even start.
Changing soils or methods can impact that process and then you go back to the drawing board, but it's always easier to power through once you accomplish it the first time.
Relative to what i do, i have to drop N ~40ppm or so as i get into flower to avoid dark glossy leaves later on. I start this process about 10-14 days before flower (relative to a ~40 day vege phase). Someone who doesn't feed N as heavily as i do leading up to that point, may need a less profound shift or none at all.
concepts and logic translate, but exact directions will vary unless someone does things in a very similar way to you from day 1....
and, even messier differences between gardens if not soilless/hydro. Just a fact of how those methods work.. they center around precise control of nutrition around the roots and fewer unknown variables given the media and fertilizer products used. In the end, the concepts remain the same even if one method involves a bit more trial and error to flesh it out.
To ensure i am not over-feeding mid-to-late flower, i like to see a very slow degredation of the canopy... definitely don't want it getting more lush over time at that point. either maintaining or slowly degrading.. .and at a rate that can't possibly result in a decimated canopy before harvest takes place. Can't manifest mass from the ether....