If an offer specifies no time limit and which to accept the offer he has 30 days to respond offer he has 10 days to respond offer is not valid and therefore it does not matter when the offer you responds or offer he has a reasonable period during which to accept
the offer. This reasonable period will depend on the circumstances of the offer and the parties involved. It could be a few days or weeks, but it must be within a reasonable timeframe. If the offeree takes too long to respond, the offer may be considered withdrawn by the offeror.
In general, it is best practice for the offeree to respond to an offer in a timely manner to avoid any confusion or potential legal issues. If there is any uncertainty about the validity of the offer or the timeframe for acceptance, it is recommended to seek legal advice for clarification.