You can obtain extra informations about the instance you just spawned : its CPU usage, the memory, the disk io or network io, per instance, by running the nova diagnostics command:
$ nova list
+--------------------------------------+------+--------+------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+------+--------+------------------------+
| 50191b9c-b26d-4b61-8404-f149c29acd5a | test | ACTIVE | local-net=192.168.4.35 |
+--------------------------------------+------+--------+------------------------+
$ nova diagnostics 50191b9c-b26d-4b61-8404-f149c29acd5a
+------------------+------------+
| Property | Value |
+------------------+------------+
| cpu0_time | 9160000000 |
| memory | 524288 |
| memory-actual | 524288 |
| memory-rss | 178040 |
| vda_errors | -1 |
| vda_read | 3146752 |
| vda_read_req | 202 |
| vda_write | 1024 |
| vda_write_req | 1 |
| vnet0_rx | 610 |
| vnet0_rx_drop | 0 |
| vnet0_rx_errors | 0 |
| vnet0_rx_packets | 7 |
| vnet0_tx | 0 |
| vnet0_tx_drop | 0 |
| vnet0_tx_errors | 0 |
| vnet0_tx_packets | 0 |
+------------------+------------+
