41 C.F.R. § 301-50.7
Yes, you should use the online self-service booking tool offered by ETS or your agency's TMS until ETS becomes available to you.
41 C.F.R. §301-50.7
Note to § 301-50.7: Some extenuating circumstances for which you may not be able to use online self-service booking are (1) when you are attending a conference where the conference sponsor has negotiated with one or more lodging facilities to set aside a specific number of rooms for conference attendees and to ensure that a set aside room is available to you, you are required to book lodging directly with the lodging facility, (2) when your travel is to a remote location and it is not possible to book lodging accommodations through the TMS or ETS, or (3) when such travel arrangements are so complex and circumstance will not allow you to book your travel through an online self-service booking tool.