a TOTALLY OBSCURE poem about missing a son (only joking about the obscure part :)

[ChristopherSea]

Hey fim, I like the intentions herein and the mix of slant and true rhymes! It seems that the first 5 stanzas are about you though and try to set up the final one, but that may fall short of expressing your love for your son. Perhaps another stanza would help reinforce that.

In just half the time it takes to blink
or glance at a shooting star,
in the instant between one second and the next
my mind can wander far … (delete ‘... ‘) I like the long line/short line meter...

and wide in inexplicable directions, ...but then the meter changes
for reasons often imperceptible or oblique 'imperceptible' and 'oblique' may be redundant
only to return in that fraction of a second ‘second’ used again
to the present (until my next retreat). Remove parenthesis

Vanishing on the notion of a restless brain’s whim too long, ‘Vanishing on the whim of a restless brain’
to far-off destinations in but a sliver of time, ‘but’ is not needed
then back before it is evident
there occurred a vacancy of my mind. 'that there was a vacancy in my mind'?

A spontaneous smile might be a tell-tale sign
that I slipped away then returned
between two words in a sentence, I like this!
before an absence was suspected or discerned. The two choices again

But as age becomes a credential
that curries favor of privilege or price I like ‘curries’
I seem to linger and stretch the slivers
because the excursions engender such delight you don’t need 'such'

I miss you my son, my Daddy’s Boy; Sweet!
competitor who swam in lane 2. too impersonal
So much so that even amidst life’s unending bustle you don’t need ‘even’
each day I spend many moments with you. Seems incomplete, maybe another stanza

I hope this helps you in the second edit
Cheers/Chris