Find the highest point on your kitchen floor where wall and floor meet. A laser leveller is the best tool for this task.
Mark a horizontal line 150mm above the highest point around your walls. This line will indicate the bottom line of your run of base cabinets. You can adjust each cabinet leg to ensure your base cabinet run is horizontal.
Draw a second horizontal line 720mm above the bottom line. 870mm is the height of your base cabinets including the 150mm plinth so this will give you the level position for the top of each cabinet.
Check how square your kitchen corners are if you have included any base corner cabinets in your kitchen.
You now have the horizontal position for your base cabinets marked out. Using your kitchen plan, mark out the approximate width of each cabinet on to your wall to check that service elements are positioned as you want them.