Frozen ATPL
There is no such a nothing like Frozen ATPL!
What it means is that you have passed ATPL theory subjects and the only license you hold is your CPL ME-IR. You will acquire ATPL after 1500hrs (for most countries). Not sure about Kenya.
From my personal experience, alot of people focus on building PIC hrs until they hit the magic number 1,000hrs! Then you start studying for your ATPL. If you hold a FAA license, you just do a pratical test and a checkride!