Fastest way to set up MySQL replication from backup
For the Sake of this Post

IP of Master is 10.20.30.100
IP of Slave1 is 10.20.30.110
IP of Slave2 is 10.20.30.120
IP of Slave3 is 10.20.30.130

ALL InnoDB
If all your tables are InnoDB, you can do this:
STEP 01 : If you do not have binary logging enabled, you need to enable it. Here is how you can tell:
Login to MySQL and run this
mysql&gt; SHOW MASTER STATUS;

If you get something like this:
mysql&gt; show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000266 |      120 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

then, it is enabled. If you get Empty Set, then it is not enabled.
To enable it, add this to your my.cnf
[mysqld]
log-bin=mysql-bin

and restart mysql
STEP 02 : Create a Replication User on the Master
Run this
GRANT REPLICATION CLIENT,REPLICATION SLAVE ON *.*
TO replicator@'%' IDENTIFIED BY 'replicationpass';

STEP 03 : Test the Replication User
On each of the Slaves, run this in Linux
MASTER_IP=10.20.30.100
mysql -h${MASTER_IP} -ureplicator -preplicationpass -ANe&quot;SHOW VARIABLES LIKE 'hostname'&quot;

Make sure it echos the hostname of the Master from all Slaves.
STEP 04 : Clear all binary logs on the Master
Simply run
mysql&gt; RESET MASTER;

To clear away all binary logs and start with a fresh one
STEP 05 : Dump all your data to a text file
From
MASTER_IP=10.20.30.100
echo &quot;CHANGE MASTER TO master_host='${MASTER_IP}',&quot; &gt; LoadSlaveData.sql
echo &quot;master_post=3306,master_user='replicator',&quot; &gt;&gt; LoadSlaveData.sql
echo &quot;master_password='replicationpass',&quot; &gt;&gt; LoadSlaveData.sql
echo &quot;master_log_file='bogus',&quot; &gt;&gt; LoadSlaveData.sql
echo &quot;master_log_pos=2;&quot; &gt;&gt; LoadSlaveData.sql
DUMP_OPTIONS=&quot;-single-transaction --master_data=1 --routines --triggers&quot;
mysqldump --uroot -p ${DUMP_OPTIONS} --all-databases &gt;&gt; LoadSlaveData.sql
echo &quot;START SLAVE;&quot; &gt;&gt; LoadSlaveData.sql

Line 28 will have the binary log and position for replication because of --master_data=1.
STEP 06 : Load the SQL file into each Slave
Login to Each Slave and Load that File
mysql -h10.20.30.110 -uroot -p &lt; LoadSlaveData.sql
mysql -h10.20.30.120 -uroot -p &lt; LoadSlaveData.sql
mysql -h10.20.30.130 -uroot -p &lt; LoadSlaveData.sql

THAT'S IT. NO DOWNTIME
ALL MYISAM or SOME InnoDB / SOME MyISAM
What you proposed in your question is more of a fit for databases with any MyISAM tables
I have recommended the same technique over the years

Nov 09, 2012 : How can I reinitialize some MyISAM tables without restarting MySQL?
Jul 24, 2012 : How to copy a MySQL database which is a mixture of InnoDB and MyISAM to the same server?
Mar 15, 2012 : Why is mysqlhotcopy slower compared to rsync?
Jun 17, 2011 : What is the difference between XtraBackup and rsync?

I even mentioned this in StackOverflow : MySql - create replication with minimal downtime