The birds will know when the grapes are getting sweet so I'd wait a while until you notice that they are almost getting sweet. Do organza bags breath letting in air to circulate inside?

For best quality and ease in harvesting grapes should be heavly pruned annually so plants stay compact (some verities more so than others). Bird net or fish net for tightwads can be stretched over plants anytime without effecting them. I harvest bamboo growing wild around bridges and use it to support net tent 4' above ground at edges so that I can bend and duck under to tend and harvest crops without removing net. Not 100% bird proof but plenty good enough.

I have one plant trained along my small garden hut. I get roughly 10 to 15 bunches

I put the baggies up when the grapes have a nice size but are still green-ish

last year I put a lot TLC in the process, trimmed out single, mushy grapes (after a rainy spell), shortned the bunch so it woul hang free within the bag and checked thet the bunchlets were not tangled or criss-crossing.

on another garden forum, someone posted a japanese video how they produce extra large berries on medium sized bunches. That was inspirational but too much effort even for me,

but this is actually effective to improve quality

so, that was from last season, it had record size due to lots of rain in the growing weeks

it helps, but I still had wasps gnawing through it, weird worms/ caterpillars developping within the bag (too late...)

and that was from few years back when I was still experimenting

Sounds like I need to wait a bit until they're bigger; I'll give it a few more weeks.