Is it true that now we must have an at least 6-month old blog or site if we want to apply for Google AdSense for the first time?
I believe a strict age requirement is only applied to blogger blogs. You should have a completed website before applying to Adsense though. Make sure you have some posts, or you may get rejected.
If you are in India or China or some other locations your site must be at least six months old, whether it's a blogger blog or not. As starfall points out, age isn't enough, it also has to be a completed site that meets all the Adsense Program Policies. Read Google's help information: Is my site eligible to participate in Adsense?
I don't think there is a specific length of time that the site/blog needs to have in order to be accepted. Some people are accepted with a few days old Blogger blogs, but usually they have already placed quite some content in them. So, I'd say the most important factor is (quality) content. For some countries, though, there may be different terms, as pointed.
Age of site / domain is a factor before Google allows adsense accounts and as already pointed out - some countries have at least 6 month restriction in place so it would be wise to check latest rules on google site itself.
i think there is no specifec time, when we must apply adsense?. But if the question is "When i put adsense in my website or blog?" I recommend 3 month after your website online. Because i think google is very like content so in 3 month, optimize your web with content then put your adsense...but i recommend you read the TOS too...
you can apply same day. There really is no time frame, however it never hurts to wait awhile before applying.
actually, no, you don't have to have a TLD, you can apply using blogger, also blogger makes your chances of being accepted higher
totally agree with you, i am in China and the domain must be at least six months old before applying the Google AdSense.