I am wondering if it is now safe to order and avoid the first production batch.
As a rule I try not to be,first, preferring to buy when production teething problems have been found and addressed..
Is it too soon or safe yet?
You could try sending an email to hello@planetcom.co.uk and ask how large they expect the first batch to be. If so, please tell us their answer, if any (they're likely quite busy right now), and I suppose, at this point, they don't know for sure anyway.
Based on an Early Gemini update, the target for the first Gemini batch was 2000 devices, the first 1000 of which ended up without eSIM, the wrong SoC and some keyboard irregularities spread seemingly at random among early units - though mine works fine, with a piece of sticky tape in the right place. They've said they're working with the same factory this time, so we can deduce it has capacity for a first batch of at least 2000 devices, though any glitches are of course more likely earlier in the run.
When 6 out of 999 Early Bird units were left to back, they hiked the number to 99, so as of now, there are 999 - 6 + 99 = 1092 Early Bird units, of which 1053 are claimed right now. Adding 17 packs of two and two packs of five = 1097 backed units with an estimated delivery of May 2019. When the Early Bird offer briefly ran out, before they increased the offer from 500 to 750 units, the "regular" $599 crowdfunding offer that appeared, had an estimated delivery of June 2019, just like the Gold Edition.
Taken together, that would suggest they plan a first batch, likely covering all Early Bird units as well as the packs of two or five. My guess would thus be that all Early Bird units will be made in the first batch. If you feel a need to stay clear of the first batch, I'd suggest you wait until there's an offering with a later estimated delivery date than the Early Bird units, though that may mean your device will cost a tad more.
My personal opinion is that whatever issues aren't found in the first 500-1000 units are likely things not apparent in the factory (like hinges getting loose over time) so to avoid "production teething problems", I'd say you're good now, but I am know to have been wrong more than once.