What is a good amount of Bitcoin to buy for first time buyers new to the crypto market?
Any amount that you can afford to lose and is willing to invest. There is really no minimum.
What kind of return can you expect to see within a week?
You can't really predict this kind of returns. You can easily lose a lot of money if you are not patient and don't have the nerves to watch your money getting burned.
If you had bought 1 Bitcoin last week (~$4600), you would have lost ~$1220 by now - yes, ~26% in one week. The same way that if you had done the same buy two months ago, you would have profited $1500 or $2800 if you have sold at the top. Bitcoin is very volatile and if you don't know what you are doing, you will end up regretting.
Referring us back to this post, it has answer the question, let say you hold your bitcoin or buy some good amount of bitcoin in the last couple of weeks ago you will be standing to gain a fortune by now.