I am not entirely sure that a specific "safety" talk is such a good idea. Such things tend to focus on tools, materials, and procedures....not bad things in themselves, but a step backwards if "safety" stops there. Indeed, too many times I have seen "safety" degenerate into kangaroo courts, and absolutely absurd positions being advanced as doctrine.
In the "History of Safety", the original emphasis was on tools and equipment; this led to statistical improvement that quickly levelled off. The next step was a focus on procedures...and again, a quick improvement occurred, that quickly levelled off. The third 'step' was a focus on management- and the "corporate culture." Great improvements were being made- and then OSHA was created. Back we were to focusing on 'parts and policies-' and the accident rates went right back up! Statistically, it was as though we instantly regressed 12-15 years! And improvement has been ever so slow since then.
Rather than a dedicated "safety talk," scheduled at a specific time, I would look for a more general 'time out,' at irregular intervals, to implement housekeeping, training, and discussion/ feedback. As an example, on your way to work you might observe that your driving was affected momentarily by some fool who just had to honk his horn at the pretty lady at the bus stop. On the job site, this can be applied to improving both work and safety by reducing unnecessary distractions.
Safety has to be an integral part of the job- not just the first ten minutes on Monday morning! And, statistics proove, the source is with management- not the poor sod who get hurt!