How long will a company wait till the h1b petition gets approved?

I am on h4 and plan to change to h1.Since companies start filing for h1b petition after April and one can start working only after Oct.Why will the company wish 2 wait for more than 5 months?what will be the appropriate time to look for jobs, that is how long will companies wait?

You are correct. Lot of companies are not willing to wait and that’s why prefer candidates on F-1/OPT who can work while the petition is under process. You can still approach consulting companies who will be more willing to wait (but also more prone to denials) and later move to a better employer.