TN and H1-B from Company A to Company B

[Jay_Kay]

I was on TN with Company A and they also submitted H1-B application which got approved. However, my contract with them ended on August.
While I was on the 60 day grace period I got an offer with Company B. I applied for new TN (for Company B) and it was approved. They also want to do my H1B transfer.

Question:
1) Company B mentioned once my H1-B becomes active (October 1st) they will do the transfer within 30 days.
I am unsure about why it can't be done asap instead of waiting for few days. I asked them this question and they said that's what their lawyer mentioned.

Is it ok for the H1-B transfer to be done within the 30 day period? Any negative impact it will have if done during that time period?

2)
a) Should I be worried that my H1B will be revoked by Company A? 
b) Is there any way to see if the H1-B is revoked? (I've been checking using the receipt number, is there another way?)

Any guidance on this is greatly appreciated! Thank you!

[gopalakrishnach]

2)
a) Should I be worried that my H1B will be revoked by Company A?  - this is normal and as per law.