Help with configuring DbContext with EntityFramework using good practices

I have my application layered with Class Library and my layer with Entity Framework , where I set DbContext , it's Repository .

My class inherited from DbContext:

public class Context : DbContext
{
    private static string connectionString = "Data Source=(local); Initial Catalog=CRM; Integrated Security=True;";
    public Context() : base(connectionString)
    {
        // Set the auto versioning
        Database.SetInitializer(new MigrateDatabaseToLatestVersion<Context, Migrations.Configuration>()); 
        // Gets or sets the database initialization strategy. 
        Database.SetInitializer<Context>(new Repository.DatabaseAdditionalConfigurations<Context>());
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // Pluralizing
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        // Non delete cascade
        modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
        // Configure Pessoa
        modelBuilder.Configurations.Add<Domain.Pessoa>(new Domain.PessoaTypeConfiguration());

        base.OnModelCreating(modelBuilder);
    }

    #region DbSet´s ...
}

Notice that the first line of the constructor is for auto-database migration using Migrations : Database.SetInitializer(new MigrateDatabaseToLatestVersion<Context, Migrations.Configuration>()); .

Is this a good time in the class life cycle for this line to be? Or should it be left out in another context?

And I also created the UniqueKeyAttribute class to configure the fields that are unique in my database:

using System;

namespace Domain.Attributes
{
    ///<summary> 
    ///A unique attribute 
    ///</summary> 
    public class UniqueKeyAttribute : Attribute { }
}

And for this attribute to be translated into the database I've added the following class, which unfortunately can not remember the source:

public class DatabaseAdditionalConfigurations<T> : IDatabaseInitializer<T> where T : DbContext
{
    public void InitializeDatabase(T context)
    {
        var created = false;

        if (context.Database.Exists())
            created = true;
        else
            context.Database.CreateIfNotExists();

        if (!created)
            CreateUniqueKeys(context);
    }

    public void CreateUniqueKeys(T context)
    {
        //Fetch all the father class's public properties 
        var masterProperties = typeof(DbContext).GetProperties().Select(x => x.Name).ToList();

        //Percorre cada DBSet<> do DbContext
        foreach (var item in typeof(T).GetProperties().Where(p => masterProperties.IndexOf(p.Name) < 0).Select(x => x))
        {
            //busca o tipo de "T" 
            Type entityType = item.PropertyType.GetGenericArguments()[0];
            // Cria as chaves únicas
            var fields = from f in entityType.GetProperties()
                         where f.GetCustomAttributes(typeof(Domain.Attributes.UniqueKeyAttribute), true).Count() > 0
                         select f.Name;

            var uniqueKeys = "";
            foreach (string s in fields)
            {
                if (string.IsNullOrEmpty(uniqueKeys) || string.IsNullOrWhiteSpace(uniqueKeys))
                    uniqueKeys = s;
                else
                    uniqueKeys += ", " + s;
            }
            if (!string.IsNullOrEmpty(uniqueKeys) && !string.IsNullOrWhiteSpace(uniqueKeys))
                context.Database.ExecuteSqlCommand("alter table " + entityType.Name + " add unique(" + uniqueKeys + ")");
        }
    }
}

Well, first I have a problem. Now that I've added the control with Migrations I do not know when I can set the Database.SetInitializer<Repository.Context>(new Repository.DatabaseAdditionalConfigurations<Repository.Context>()); setting so that the CreateUniqueKeys method can create the unique keys in the database. How could I treat this? Would it be in method Seed of class Configuration of Migrations ?

Another issue is that my base was automatically created only when% of the builder of the Migrations Configuration class was set to AutomaticMigrationsEnabled = true; . Do you need this, or am I doing something wrong? Is going this route a good practice?

Remembering here the ideal place question for: true .