Your question is 3 days old so may be you heard something new since then.
The appraisal is usually ordered after the home inspection is done and after the option period has expired. On the contract's third party financing addendum there is a number of days that the buyer has to get "FULL LOAN APPROVAL" by. See how close you are to it.
Depending on the lender they are using, sometimes they do wait for loan approval b/4 they order the appraisal. Your Realtor should be able to answer that.