sentences for bank robbery consecutively or concurrent ly. However, the statute does not permit the court to decide whether any future sentence would be consecutive or concurrent to those five sentences. Rather, when sentences are imposed at different times, § 3584(a) only authorizes a court to determine whether a sentence should be consecutive or concurrent if the defendant is “already subject to an undischarged term of imprisonment.” 18 U.S.C. § 3584(a) (emphasis added). Another sentence must exist at the time a district court imposes its sentence; a court cannot impose its sentence consecutively to a sentence that does not yet exist. The better-reasoned cases from our sister circuits have reached the same conclusion. See Romandine v. United States, 206 F.3d 731, 738 (7th Cir.2000) (<HOLDING>); United States v. Quintero, 157 F.3d 1038,
holding that a term of imprisonment begins at the time a prisoner is sentenced holding that   3584a allows the district judge to specify the sequence of service of terms of imprisonment only when sentences are imposed at the same time or the other sentence is an undischarged term of imprisonment to which the defendant is already subject  holding that  5g13c applied because the defendants case involved multiple undischarged terms of imprisonment only one of which was used to enhance his instant sentence holding that the term of imprisonment for purposes of application note 5 is the sentence imposed by the state court and that it shall not be decreased to reflect a suspension of any part of the sentence holding that the concurrent sentencing requirement of  5g13b  is only triggered when there is an undischarged term of imprisonment at the time of sentencing