No, it's not really a problem. Assuming you're there to re-assign them.
The big problem is if you make sure you can survive a normal winter (-75% catnip rate), leave the game idle for a while (say overnight), and at some point, a cold winter hits (-90% catnip rate). If a kitten dies while you're idling, then the new kitten to arrive won't be assigned a job until you get back.
There are a few achievements related to starving kittens, though. You need to starve kittens for two of them (one at ten dead kittens, one at 100), and another comes for reaching 50 kittens without any dying. You don't need to worry too much about missing that last one, though; it's easier after a reset or two anyway.
Of course, the real question is: are you going to live with yourself after letting a poor innocent kitten starve to death?
Looking at the code, the skills' information is as follows:
- Dabbling - No XP required - No bonus
- Novice - 100 XP required - 1.25% Bonus
- Adequate - 500 XP required - 2.5% Bonus
- Competent - 1200 XP required - 4.5% Bonus
- Skilled - 2500 XP required - 7.5% Bonus
- Proficient - 5000 XP required - 12.5% Bonus
- Master - 9000 XP required - 18.75% Bonus
Thus, a kitten who is splitting their time up between two jobs about evenly is going to still be under proficient when a kitten who'd focused on the same job all the time has made master. You're probably better off letting a small number of kittens focus on Farming continuously through the year; you won't get much benefit right away, but when they finally do make master, they'll be able to feed more kittens, especially with the upgrade later on that doubles how much bonus all skills give.
Even worse, any kitten who has skill in a job they're not currently doing, will slowly (very slowly) lose experience in that job. The effect of this is minor (five thousandths of an XP per second), but if you're idling for long stretches, it can stall progress if you're trying to teach a kitten two jobs.
In the end, though, it doesn't matter too much what you do this early in the game. Getting to master-level kittens takes a while, and swapping your kittens around won't stop them from making master in their jobs eventually; just slows it a little. Plus, once you get more Pastures, and the Hoe upgrades to your farmers, even a small handful of Dabbling farmers will be enough to feed a fairly large population through cold winters.
Best Answer
Ivory, like Furs, is automatically used up over time to provide a Happiness boost to your kittens. If the amount of Ivory you generate per tick doesn't exceed the amount automatically used per tick, you'll be unable to stockpile any. Furthermore, the Mint will only actually generate Furs and Ivory if you have enough Catpower and Gold to spend running the Mints; if you have a net negative of either of those resources, the Mints will only generate Furs and Ivory on the ticks in which a full tick of those resources can be spent.
The left sidebar shows details about all your resources, including net generation rate. Hovering your mouse cursor over the generation rate will show details for everything that is producing or consuming that resource. However, this rate may not reflect the actual rates if you're expending more of a resource than you're making (e.g. the Ivory rate won't visibly change if you run out of Catpower or Gold, as long as you're still making some Catpower and Gold).
If you want to stockpile Ivory, you can increase your generation rate by having more Mints active, or reduce demand by building Tradeposts.