An old documented way of preventing services from starting immediately after installation in Debian/Ubuntu is using the RUNLEVEL environment variable to trick the runlevel helper into returning a response that the system isn't fully running, such as:

# RUNLEVEL=1 apt-get install nginx

Sadly this doesn't work in newer versions …

DigitalOcean offers some fantastic KVM powered virtual machines for low prices, however the technical decisions they've made in various places leaves something to be desired.

One of the problems which you may face at some point is that you're stuck with whatever kernel they provide, you can't use your own …