Passing date parameter into a GDS streaming algorithm

[stu_v_kerr]

Using both Neo4j 3.5.x and 4.x
I am trying to pass a date that is computed using apoc as a parameter into the gds.nodeSimilarity.stream. A code snippet is below:

:param start=>{RETURN apoc.date.format(apoc.date.add(timestamp(),"ms", -60,"d"),"ms","yyyy/MM/dd") as start};
CALL gds.nodeSimilarity.stream(
{
nodeQuery: 'MATCH (n) WHERE n:Reader OR n:Title RETURN id(n) as id',
relationshipQuery: 'MATCH (n:Reader)-[r:READS_TITLE]->(t:Title)
WHERE r.readingDate > "$start" and ...
})

Is this how to pass a parameter into a GDS algorithm? The two sections of code successfully complete in the browser but no results are returned. When I hard code the date into the GDS algorithm, results are returned.
Thank you for any advice and recommendations