You can set your min card pool level to 2 to get the same effect as waiting for expansions:
You can even put it higher, to make sure even more cards are in the pool from where the kingdom is selected.
OTOH, since subscriptions run on level 1 (free, no subscription), 5 (core subscription) and 10 (complete subscription), the next level after 2 to make a difference is likely 6. In theory players who use lots of promo codes may have ean effective card level somewhere in between, but those are IMO rare.
You can even put it higher, to make sure even more cards are in the pool from where the kingdom is selected.
OTOH, since subscriptions run on level 1 (free, no subscription), 5 (core subscription) and 10 (complete subscription), the next level after 2 to make a difference is likely 6. In theory players who use lots of promo codes may have ean effective card level somewhere in between, but those are IMO rare.