It is an anachronism in New York practice that there is no specific time in which to name an expert.  While the 3d and 4th departments have rules that derive from case law [and not specifically, the CPLR], the 1st and 2d Departments are much looser.  In general, a "reasonable time" period obtains.  There are some courts which will require that the expert be named 30 days or 15 days prior to trial,  there is no unanimity of what day that might be.  Is it the first day of jury selection?  is it the first day of testimony? 

On a finer level of analysis is the relationship of naming an expert pursuant to CPLR 3101 and motions for summary judgment.  In the 2d Department, especially Kings County, a body of law has arisen which holds that one must name an expert and serve a CPLR 3101 notice prior to the note of issue.  Here is an excerpt from Sierra v. D’Apuzzo, 6321/08;Decided: April 21, 2010;Judge Robert J. Miller;KINGS COUNTY;Supreme Court

"Before the Court considers whether the landlord caused or created the condition or had actual or constructive notice of the condition, the Court must first address the threshold issue of whether the plaintiff’s expert’s affidavit should be considered in opposition to the defendant’s motion. The defendant in reply to the plaintiff’s opposition asserts that the Court should reject the plaintiff’s expert’s report pursuant to Construction by Singletree, Inc. v. Lowe, 55 AD3d 861 [2d Dept 2008]. The Appellate Division, in Singletree rejected a plaintiff’s expert affidavit in opposition to the defendant’s motion for summary judgement because the plaintiff’s expert was not identified until after the note of issue and certificate of readiness were filed and the plaintiff offered no valid excuse for failure to give notice of the expert.

Here, plaintiff filed her note of issue and certificate of readiness attesting to the completion of discovery on July 29, 2009. The defendant moved for summary judgment on September 25, 2009. Plaintiff served her CPLR3101(d) response on October 12, 2009 and did not serve her expert affidavit until she served her opposition to the defendant’s summary judgment motion. Plaintiff offers no excuse for the delay.

However, at oral argument on the motion, the plaintiff raised the issue that the defendant did not serve his expert’s affidavit until the defendant submitted his summary judgment motion. The Court has not been provided with any discovery orders issued prior to the note of issue and certificate of readiness and therefore cannot opine on what demand or schedule of exchange may have been agreed upon by the parties. Any exchange of expert reports to be used in a summary judgement motion should have been exchanged prior to the note of issue and certificate of readiness following the ruling in Singletree.

The Court notes that the plaintiff’s expert Robert C. Schwartzberg’s report indicates he visited the scene of the accident on July 27, 2009 (two days prior to the note of issue and certificate of readiness were filed) and wrote a report dated August 20, 2009. The defendant’s expert, Mark I. Marpet, visited the scene on September 10, 2009 and wrote a report dated September 22, 2009.

Here, since both parties submit expert reports that are written after the note of issue and certificate of readiness were filed, the Court, in its discretion, declines the defendant’s request to reject the plaintiff’s expert report and considers both the defendant’s and the plaintiff’s expert reports. (Howard v. Kennedy, 60 AD3d 905 [2d Dept 2009].)"