Various configuration settings and syntax on applying

juju boostrap conjure localhost --config apt-http-proxy=<proxy> --config apt-https-proxy=<proxy>
Note also use for creating new models

juju add-model <name> does not inherit the config settings from the previous bootstrap.

juju bootstrap conjure localhost --bootstrap-series=xenial
juju bootstrap conjure localhost --config image-stream=daily

Hooks will normally be re-triggered which can sometimes make it hard to debug an issue in the author's charm. You can disable the automatic hook retry with the following:

juju set-model-config automatically-retry-hooks=false