How many days after my Visa stamp in Passport I must be in the USA?

I am from India,[b] I got H1B visa  in the February month (i.e. on 02/07/2013) [/b]to work in the USA. I have indicated my intended date of arrival as 03/08/2013 (8th March 2013) in the DS-160 form. But due to some unforeseen reasons I could not able to make it as I mentioned. Now I am proposing to plan my travel in the 3rd week of April'2013. Some of my friends told me like I should be in USA to work within a two months from the date of H1B visa stamp in the passport, and even though if I am not there My employer has to pay the taxes to federal government. Is it true.



My underlined important question is, is there any constraint like one should be there in USA  within the stipulated time period from the date of H1B visa stamp. Please help me in this regard.



Regards



Venkat

It is ok to delay the travel. You can use it anytime during its validity period. However, always carry recent dated documents related to your employment when traveling to US. Your employer should also agree to your travel plans.