WooCommerce - Variable product with custom from price label

functions.php

function custom_variable_price_html( $price, $product ) {
	$price = '';

	if ( ! $product->min_variation_price || $product->min_variation_price !== $product->max_variation_price ) {
		$price .= '<span class="from">' . __( 'A partir de' ) . ' </span>';
	}

	$price .= woocommerce_price( $product->get_price() );

	return $price;
}

add_filter( 'woocommerce_variable_price_html', 'custom_variable_price_html', 10, 2 );