Lot's of good answers given. Welcome to the learning portion of your
lifelong IFR classroom.

I would add that if you ever find yourself changing altitude without ATC
prompting or as the result of a specfic clearance (plan means nothing),
something is wrong.

Hey, don't stop filing on those VFR days - it really helps learn the
system without IMC distractions.

Wizard of Draws wrote:
I took a short XC today after a layoff of a few months due to real life
constraints and weather. I filed IFR even though it was VFR because I wanted
to get back into the groove of communicating with ATC.
I filed for 5000 going east. On the ground, they told me it would be faster
if I took off VFR and opened my plan in the air, so I did.

I was at 5500 when I finally got through since I was VFR, but all I was
given initially was a squawk code with no altitude assignment or clearance.
I assumed that I was IFR at this point so I began to descend to 5000 per my
flight plan. As I did I asked ATC if he had an altitude assignment, and he
came back with 6000, cleared direct. No problem, I pull back up and fly as
I'm told.

So, was I IFR as soon as I was given a squawk and required to fly my flight
plan, or should I have waited to change from a VFR altitude to an IFR
altitude until I was given specific instructions?