We normally start with the corner cabinets.  Use the adjustable legs to get the back of the cabinet level with the guide line we drew on the wall earlier.  Use the level across all directions including front to back.  Getting your levels correct at this stage is very important.

As you continue adding the cabinets ensure they are level to each other.

Join the cabinets to each other using the carcass joining screws. Continue checking everything is level as you go.

Push the sink cupboard up against the plumbing for your taps and mark the location to cut out holes to suit.

Use a hole saw to cut out where you marked.

Place the sink cupboard its final location and mark where you will need a hole for the waste pipe.

Use a hole saw to cut in the correct location and fix the sink cupboard into place.  Check again for levels before permanently securing it to the wall and cabinets next to it.

You will need to assemble your oven base as above if you have an under bench oven.

Check that it is level across...

...and front to back.

Once all cabinets are in place put the benchtops on to make sure they fit.

Don't fasten them into place yet, we may need to move them to do the cut outs.

You are now ready to do the sink and cooktop cut outs.