waiting for input bluetooth data

I want a help with writing this small program
I want to want to receive data from bluetooth but I want to wait a minute , If nothing is received, a sentence is printed on the serial monitor
The only problem is I cant figure out "the wait ""

You need something along these lines (pseudo code). I am assuming the period starts when you send a request for data.

when data is requested {
  dataRequestTime = millis()

if (millis() - dataRequestTime >= timeoutPeriod) {
  // we have been waiting too long

Have a look at the examples in Serial Input Basics - simple reliable ways to receive data.