关于美国移民,收到移民局寄来的信,请问还要等多久?

关于美国移民,收到移民局寄来的信,请问还要等多久?
信的内容如下
the enclosed information pertains to your interest in immigrating to united stattes of america.the inforrmation conceerning your registration is noted at the end of the letter.
unfortunately,visa numbers are not presently available for your use.you will be notified whenfurther consideration can be given to processing your application for immigration.the reasson
for this delay is that there are more applicants for visas than theree are immigrant visa numbers aavailable under the limitation prescribed by law.for some visa categories,for example F3 or F4,this delay could be many years.should you wish to know which priority dates are currently being processed,you may call the State Department's visa office at(202)6631542.
you are cautioned that you must not make any firm plans,such as disposing of property,giving upjobs,or making travel arrangements at this time,we have no way of predicting when it will be possible to proceed whit your immigraant visa application.
you need not check with us further unless you need to report a change of address or a change in you personal situation which may affect your entitlement to an immigrant visa.
we will keep your case on file until further action is possible,when communicating with this of either by telephone or letter,you must always refer your name and case number exactly as the appear below,