You can fix this with Reposition in the Browse window. Browsing - Anki Manual
- Get all of your New cards in view – search
is:new. [For this to be effective, you need to do this on your whole collection, even if you don’t study all of the cards together.] - Sort them by the “Due” column – so they will be in New-queue # order.
- Select All > Cards > Reposition.
- Make a note of where the “queue bottom” currently is (out in the 7 figures).
- Choose start 0 [or see below], step 1, boxes both unchecked. OK.
- Tools > Check Database.
When that finishes, you can open the Reposition box again, to see where your new “queue bottom” is.
The New-queue numbers only matter relative to each other, so it doesn’t matter if they are consecutive. And if there are blocks of cards that you want to be introduced before/after other blocks, you can Reposition those relative to each other too.
There’s no option to do that, but there is a way to approach it. At step 5 above, set your “start” to something higher than 0 (100? 500?). This will create “room” at the front of the queue, and make your newly added cards more likely to be created there.
Sometimes though they will still be created at the end of the queue. At the end of the day when you’ve been adding cards, you can search up those New cards with added:1 and check their New-queue numbers. If any of them went to the end of the queue, you can Reposition them to something closer to the front.