diff --git a/lib/periodicity/extensions/active_job.rb b/lib/periodicity/extensions/active_job.rb
index 4e40a44..5def355 100644
--- a/lib/periodicity/extensions/active_job.rb
+++ b/lib/periodicity/extensions/active_job.rb
@@ -2,7 +2,7 @@ module Periodicity
   module Extensions
     class ActiveJob
       def self.perform_every(period, *args)
-        @period = period
+        @period = Period.new(period, *args)
       end
     end
   end
diff --git a/lib/periodicity/period.rb b/lib/periodicity/period.rb
index 2e0aab7..8b5fbc3 100644
--- a/lib/periodicity/period.rb
+++ b/lib/periodicity/period.rb
@@ -1,11 +1,24 @@
 module Periodicity
   class Period
-    def initialize(period)
+    def initialize(period, at: nil)
       @period = period
+      @at_hour, @at_min = parse_at(at) if at
     end
 
     def next
-      @period.from_now
+      @period.from_now.change({hour: @at_hour, min: @at_min}.compact)
+    end
+
+    def parse_at(at)
+      case at
+      when String
+        time = Time.parse(at)
+        return time.hour, time.min
+      when Hash
+        return at[:hour], at[:min]
+      else
+        raise "Unknown 'at' format"
+      end
     end
   end
 end
diff --git a/spec/period_spec.rb b/spec/period_spec.rb
index 4605f43..4d2265d 100644
--- a/spec/period_spec.rb
+++ b/spec/period_spec.rb
@@ -13,6 +13,23 @@ describe Periodicity::Period do
         @period = Periodicity::Period.new(2.day)
         expect(@period.next).to be_eql(2.day.from_now)
       end
+
+      it "should set time to 'at' time as a string" do
+        @period = Periodicity::Period.new(2.day, at: "15:20")
+        expect(@period.next).to be_eql(2.day.from_now.change(hour: 15, min: 20))
+      end
+
+      it "should set time to 'at' time as a hash" do
+        at = {hour: 18, min: 45}
+        @period = Periodicity::Period.new(2.day, at: at)
+        expect(@period.next).to be_eql(2.day.from_now.change(at))
+      end
+
+      it "should raise error when 'at' is wrong" do
+        expect {
+          @period = Periodicity::Period.new(2.day, at: 1)
+        }.to raise_error("Unknown 'at' format")
+      end
     end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index b088166..2c822b8 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -4,6 +4,5 @@ Bundler.setup
 require 'timecop'
 require 'periodicity'
 
-
 RSpec.configure do |config|
 end