reminder user to wait for the simulated device starting sending messages instead of return {}

[czgtest]

when getting device telemetry ,return {} directly after enter component name and telemetry name as bellow.
Actually:
Please enter Component Name: Interface
Please enter Telemetry Name: Temperature
{}
Expect:
Give a message in console line and reminder to wait for the simulated device starting sending messages
then enter Component Name and Telemetry Name to get telemetry as bellow.

Getting Devive Telemetry... Please enter Component Name: Interface Please enter Telemetry Name: Temperature { "value": 60.66188318806059, "timestamp": "2020-02-21T12:03:28.449+00:00" }

[shizn]

Same issue reproduced on my end.