Define service Time inside a Queue fs2 Streams Scala - scala

Question

I'm doing some basic test with queue I want to add a service time before dequeuing the queue.
for instance, the service time is not defined, It will be a mean of 3 seconds it may vary among elements.
Can someone provide some enlightenment?
Here is what I am trying to do: For instance, for 1, it may take 3s, for 2 it may take 5s, for 3 it may take 4s ...
The idea is the mean service time for example 4 seconds...
import cats.effect.{ExitCode, IO, IOApp, Timer}
import fs2._
import fs2.concurrent.Queue
import scala.concurrent.duration._
class StreamTypeIntToDouble(q: Queue[IO, (Double, String)])(
implicit timer: Timer[IO]
) {
def storeInQueue: Stream[IO, Unit] = {
Stream(1, 2, 3,4)
.covary[IO]
.evalTap(n => IO.delay(println(s"Pushing $n to Queue")))
.map { n =>
(n.toDouble, "Service")
}
.through(q.enqueue)
}
def getFromQueue: Stream[IO, Unit] = {
q.dequeue.evalMap(n => IO.delay(println(s"Pulling from queue $n")))
}
}
object Five extends IOApp {
override def run(args: List[String]): IO[ExitCode] = {
val program = for {
q <- Queue.bounded[IO, (Double, String)](10)
b = new StreamTypeIntToDouble(q)
_ <- b.storeInQueue.compile.drain.start
_ <- b.getFromQueue.compile.drain
} yield ()
program.as(ExitCode.Success)
}
}