<mat-horizontal-stepper #stepper>
<mat-step></mat-step>
<mat-step></mat-step>
</mat-horizontal-stepper>

<button class="buttonImg" id="buttonnxt" (click)="goForward(stepper)"
type="button"></button>`

goForward(stepper) {

this.stepperCurrentIndex = stepper;

switch (this.stepperCurrentIndex) {
 case 0: {
   this.project0linking()
   //before project0linking() containing asynchronous call should
   finish after that stepper.next should be called
   stepper.next(stepper);
   break;
 }
  case 1: {
    this.project1linking();
    //before project1linking() containing asynchronous call should
    finish after that stepper.next should be called
    stepper.next(stepper);
    break;
     }
  case 2: {
    this.project2linking();
    //before project2linking() containing asynchronous call should
    finish after that stepper.next should be called
    stepper.next();
    break;
      }
  }
}

linking(){
 //http call
 Only after completion of this call stepper.next() should be called
}