Estimate database restore time

Hi, I have 2 servers <g class="gr_ gr_54 gr-alert gr_gramm Punctuation multiReplace" data-gr-id="54" id="54">with .</g> In my secondary I need to move one database from one drive to another drive.
So my plan is
1.Suspend data movement
2.remove <g class="gr_ gr_58 gr-alert gr_gramm Grammar only-ins doubleReplace replaceWithoutSep" data-gr-id="58" id="58">database</g> from <g class="gr_ gr_59 gr-alert gr_gramm Grammar only-ins replaceWithoutSep" data-gr-id="59" id="59">secondary</g> replica
3.remove <g class="gr_ gr_57 gr-alert gr_gramm Grammar only-ins doubleReplace replaceWithoutSep" data-gr-id="57" id="57">database</g> from Primary replica
4.Drop the DB from secondary
5.Take a full and log backup from primary
6.Restore with no recovery it in secondary( it's named instance)
7.Add to <g class="gr_ gr_60 gr-alert gr_spell ContextualSpelling ins-del multiReplace" data-gr-id="60" id="60">alwayson</g>
Now my team ask how much time will take to restore (for getting downtime).
In primary, the size - 15gb.
So is there any way to restore time, before it?
And also guide me to done this

<g class="gr_ gr_55 gr-alert gr_spell ContextualSpelling" data-gr-id="55" id="55">sqlalwaysonreplica</g> <g class="gr_ gr_56 gr-alert gr_spell ContextualSpelling" data-gr-id="56" id="56">dbcalcuterestore</g>