How to handle date on temp table when is null or not ?

Question

How to handle date on temp table when is null or not ?

I work on SQL server 2012 I using format dd/mm/yyyy

I need to handle date on #temp table on both of fromdate or todate .

if i have null on fromdate or todate what i do

if some one write formate date is wrong How i make it as dd/mm/yyyy

create table #temp
(
masterId  int,
fromdate datetime,
todate   datetime
)
insert into #temp values
(1,'12/01/2017','05/06/2019'),
(2,'12/02/2018','12/07/2019'),
(3,null,'12/09/2019')


select * from pcn.MasterData M inner join #temp tmp on m.MasterDataID = tmp.masterId
WHERE (tmp.fromdate is null OR tmp.fromdate >= M.InsertionDate ) AND (tmp.ToDate IS NULL OR tmp.ToDate <=M.InsertionDate)