I feel that u doesn't need to hire a sleep consultant , u can do it together with your toddler by having some patience and routine tips . Put him in his cot and dim the lights , let him roll and play in his cot . Continue to pat him and sing some lullaby song . Be prepared to wait for a couple of hours . Continue the same routine and timing tomoro , the next day and so on . He will get it by a week or two . Do it both during nap time and sleeping time .
This may help you : https://sg.theasianparent.com/how-to-get-baby-to-sleep-fast-2