Change is done each morning. If you are in space during that time, you will be warned ("Console message: Incoming Ion storm ..."). After this YOU NEED to restart game via launcher to synchronize your client and server market files. If you do not restart, then you will most likely be "kicked" right after you buy some commodities and undock from a station.
Dynamic economy does not affect containers trade, BMGs and selling NPC's escape pods to prisons.
In SP if you want to have the dynamic economy functional, you will need to download the updates on a daily basis via the launcher.
