Godolphin's Tassort is now in doubt for the Slipper with a bruised foot and has been withdrawn from Saturday's Todman with trainer James Cummings hoping he can be fit for the Pago Pago a week later.
Time To Reign worked with older sprinter Vincero at Warwick Farm on Tuesday morning.
“Time To Reign beat Vincero in the gallop and has come on since his Silver Slipper win,” Portelli said.
“He is absolutely cherry ripe. He lost two kilos after the race and put it back on within two days.
“And now we know he can cope if it's wet or dry.
“And we also know he will be going to the Slipper as fit as he can be,”
Time To Reign has won three of his four starts with his sole defeat in the Lonhro Plate won by Bivouac who is a likely Todman rival.
The Guineas will be whittled down to a maximum field of 20 from its 94 entries.
The Chris Waller-trained The Autumn Sun heads the market to add the Guineas to his Group One wins in the J J Atkins, Golden Rose and Caulfield Guineas.
Triple Group One winner Trapeze Artist is favourite for the Canterbury Stakes.